[debugger] Further stepping support in test wrapper

This CL adds further support to the test wrapper. We are now able to
run almost all mjsunit/debug-step-* tests using the inspector backend.

debug-stepframe-* tests are not yet supported since inspector does not
know a 'frame' step type.

The interface has also been improved to be able to move these tests to
inspector mostly without modification.

BUG=v8:5330

Review-Url: https://codereview.chromium.org/2466273005
Cr-Commit-Position: refs/heads/master@{#40800}

test/mjsunit/debug-break-inline.js → test/debugger/debug/debug-break-inline.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug --allow-natives-syntax
 
 // This test tests that deoptimization due to debug breaks works for
 // inlined functions where the full-code is generated before the
@@ -33,7 +32,6 @@
 //
 //See http://code.google.com/p/chromium/issues/detail?id=105375
 
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug;
 
 var count = 0;

test/mjsunit/debug-compile-optimized.js → test/debugger/debug/debug-compile-optimized.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug --allow-natives-syntax --crankshaft
 
 Debug = debug.Debug;
 

test/mjsunit/debug-evaluate-modify-this.js → test/debugger/debug/debug-evaluate-modify-this.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug
 
 Debug = debug.Debug
 

test/mjsunit/debug-evaluate-shadowed-context-2.js → test/debugger/debug/debug-evaluate-shadowed-context-2.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug --no-analyze-environment-liveness
 
 // Test that debug-evaluate correctly collects free outer variables
 // and does not get confused by variables in nested scopes.

test/mjsunit/debug-generator-break-on-stack.js → test/debugger/debug/debug-generator-break-on-stack.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug
 
 var Debug = debug.Debug;
 

test/mjsunit/debug-generator-break.js → test/debugger/debug/debug-generator-break.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug
 
 var Debug = debug.Debug;
 

test/mjsunit/debug-optimize.js → test/debugger/debug/debug-optimize.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug --allow-natives-syntax --use-inlining
 
 var Debug = debug.Debug;
 

test/mjsunit/debug-print.js → test/debugger/debug/debug-print.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax
 
 // Make sure printing different element kinds doesn't crash.
 

test/mjsunit/debug-stack-check-position.js → test/debugger/debug/debug-stack-check-position.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug --allow-natives-syntax
 
 var Debug = debug.Debug;
 var exception = null;

test/mjsunit/debug-step-end-of-script.js → test/debugger/debug/debug-step-end-of-script.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug --allow-natives-syntax
 
 var Debug = debug.Debug;
 var expected = ["debugger;", "debugger;"];

test/mjsunit/debug-step-into-json.js → test/debugger/debug/debug-step-into-json.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug
 
 Debug = debug.Debug
 

test/mjsunit/debug-step-into-valueof.js → test/debugger/debug/debug-step-into-valueof.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug
 
 Debug = debug.Debug
 

test/mjsunit/debug-step-stub-callfunction.js → test/debugger/debug/debug-step-stub-callfunction.js

@@ -25,8 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
 // Simple debug event handler which counts the number of breaks hit and steps.

test/mjsunit/debug-step-turbofan.js → test/debugger/debug/debug-step-turbofan.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug --turbo-filter=g --allow-natives-syntax
+// Flags: --turbo-filter=g
 
 // Test that Debug::PrepareForBreakPoints can deal with turbofan code (g)
 // on the stack.  Without deoptimization support, we will not be able to

test/mjsunit/debug-stepin-accessor-ic.js → test/debugger/debug/debug-stepin-accessor-ic.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug
 
 function get() {
   return 3;                       // Break

test/mjsunit/debug-stepin-accessor.js → test/debugger/debug/debug-stepin-accessor.js

@@ -25,9 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
 var exception = null;

test/mjsunit/debug-stepin-builtin-callback-opt.js → test/debugger/debug/debug-stepin-builtin-callback-opt.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug
 
 Debug = debug.Debug
 

test/mjsunit/debug-stepin-builtin-callback.js → test/debugger/debug/debug-stepin-builtin-callback.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
 // Test stepping into callbacks passed to builtin functions.
 

test/mjsunit/debug-stepin-builtin.js → test/debugger/debug/debug-stepin-builtin.js

@@ -25,9 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
 var exception = null;

test/mjsunit/debug-stepin-call-function-stub.js → test/debugger/debug/debug-stepin-call-function-stub.js

@@ -25,8 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
 var exception = null;
@@ -88,8 +86,9 @@ for (var i = 0; i < 3; i++) {
   expected_source_line_text = '   return "s";  // expected line';
   step_in_count = 2;
   // Set a break point and call to invoke the debug event listener.
-  Debug.setBreakPoint(testFunction, 1, 0);
+  const breakid = Debug.setBreakPoint(testFunction, 1, 0);
   testFunction();
+  Debug.clearBreakPoint(breakid);
   assertNull(exception);
   assertEquals(3, state);
 }
@@ -104,8 +103,9 @@ for (var i = 0; i < 3; i++) {
   expected_source_line_text = '   return "s2";  // expected line';
   step_in_count = 1;
   // Set a break point and call to invoke the debug event listener.
-  Debug.setBreakPoint(testFunction2, 2, 0);
+  const breakid = Debug.setBreakPoint(testFunction2, 2, 0);
   testFunction2();
+  Debug.clearBreakPoint(breakid);
   assertNull(exception);
   assertEquals(3, state);
 }

test/mjsunit/debug-stepin-construct-call.js → test/debugger/debug/debug-stepin-construct-call.js

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug
 
 var break_count = 0;
 var exception = null;
@@ -31,9 +30,7 @@ function g() {
   new f();
 }
 
-Debug.setBreakPoint(g, 6, Debug.BreakPositionAlignment.BreakPosition);
-print(Debug.showBreakPoints(g, undefined,
-      Debug.BreakPositionAlignment.BreakPosition));
+Debug.setBreakPoint(g, 6);
 
 g();
 Debug.setListener(null);

test/mjsunit/debug-stepin-constructor.js → test/debugger/debug/debug-stepin-constructor.js

@@ -25,8 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
 // Simple debug event handler which counts the number of breaks hit and steps.
@@ -38,9 +36,6 @@ function listener(event, exec_state, event_data, data) {
     if (exec_state.frameCount() > 1) {
       exec_state.prepareStep(Debug.StepAction.StepIn);
     }
-
-    // Test that there is a script.
-    assertTrue(typeof(event_data.func().script()) == 'object');
   }
 };
 

test/mjsunit/debug-stepin-foreach.js → test/debugger/debug/debug-stepin-foreach.js

@@ -2,24 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --expose-debug-as debug
 // Tests stepping into through Array.prototype.forEach callbacks.
 
 Debug = debug.Debug
 var exception = null;
 var break_count = 0;
-var expected_breaks = -1;
+var expected_breaks = 11;
 
 function listener(event, exec_state, event_data, data) {
   try {
     if (event == Debug.DebugEvent.Break) {
       assertTrue(exec_state.frameCount() != 0, "FAIL: Empty stack trace");
-      if (!break_count) {
-        // Count number of expected breakpoints in this source file.
-        var source_text = exec_state.frame(0).func().script().source();
-        expected_breaks = source_text.match(/\/\/\s*Break\s+\d+\./g).length;
-        print("Expected breaks: " + expected_breaks);
-      }
       var source = exec_state.frame(0).sourceLineText();
       print("paused at: " + source);
       assertTrue(source.indexOf("// Break " + break_count + ".") > 0,

test/mjsunit/debug-stepin-function-call.js → test/debugger/debug/debug-stepin-function-call.js

@@ -25,8 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
 var exception = null;

test/mjsunit/debug-stepin-property-function-call.js → test/debugger/debug/debug-stepin-property-function-call.js

@@ -25,8 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug --nocrankshaft
-// Get the Debug object exposed from the debug context global object.
+// Flags: --nocrankshaft
 Debug = debug.Debug
 
 var exception = null;

test/mjsunit/debug-stepnext-do-while.js → test/debugger/debug/debug-stepnext-do-while.js

@@ -25,8 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
 var exception = null;

test/mjsunit/debug-stepout-recursive-function.js → test/debugger/debug/debug-stepout-recursive-function.js

@@ -25,8 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
 var exception = null;

test/mjsunit/debug-stepout-scope-part1.js → test/debugger/debug/debug-stepout-scope-part1.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
 // Check that the ScopeIterator can properly recreate the scope at
 // every point when stepping through functions.

test/mjsunit/debug-stepout-scope-part2.js → test/debugger/debug/debug-stepout-scope-part2.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
 // Check that the ScopeIterator can properly recreate the scope at
 // every point when stepping through functions.

test/mjsunit/debug-stepout-scope-part3.js → test/debugger/debug/debug-stepout-scope-part3.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
 // Check that the ScopeIterator can properly recreate the scope at
 // every point when stepping through functions.

test/mjsunit/debug-stepout-scope-part4.js → test/debugger/debug/debug-stepout-scope-part4.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
 // Check that the ScopeIterator can properly recreate the scope at
 // every point when stepping through functions.

test/mjsunit/debug-stepout-scope-part5.js → test/debugger/debug/debug-stepout-scope-part5.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
 // Check that the ScopeIterator can properly recreate the scope at
 // every point when stepping through functions.

test/mjsunit/debug-stepout-scope-part6.js → test/debugger/debug/debug-stepout-scope-part6.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
 // Check that the ScopeIterator can properly recreate the scope at
 // every point when stepping through functions.

test/mjsunit/debug-stepout-scope-part7.js → test/debugger/debug/debug-stepout-scope-part7.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
 // Check that the ScopeIterator can properly recreate the scope at
 // every point when stepping through functions.

test/mjsunit/debug-stepout-scope-part8.js → test/debugger/debug/debug-stepout-scope-part8.js

@@ -25,7 +25,6 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
 // Check that the ScopeIterator can properly recreate the scope at
 // every point when stepping through functions.

test/mjsunit/debug-stepout-to-builtin.js → test/debugger/debug/debug-stepout-to-builtin.js

@@ -25,9 +25,7 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-// Flags: --expose-debug-as debug
 
-// Get the Debug object exposed from the debug context global object.
 Debug = debug.Debug
 
 var exception = null;

test/debugger/debugger.status

@@ -3,4 +3,23 @@
 # found in the LICENSE file.
 
 [
+[ALWAYS, {
+  # Issue 3660: Replacing activated TurboFan frames by unoptimized code does
+  # not work, but we expect it to not crash.
+  'debug/debug-step-turbofan': [PASS, FAIL],
+}],  # ALWAYS
+
+##############################################################################
+['gc_stress == True', {
+  # Skip tests not suitable for GC stress.
+  # Tests taking too long
+  'debug/debug-stepout-scope-part1': [SKIP],
+  'debug/debug-stepout-scope-part2': [SKIP],
+  'debug/debug-stepout-scope-part3': [SKIP],
+  'debug/debug-stepout-scope-part4': [SKIP],
+  'debug/debug-stepout-scope-part5': [SKIP],
+  'debug/debug-stepout-scope-part6': [SKIP],
+  'debug/debug-stepout-scope-part7': [SKIP],
+  'debug/debug-stepout-scope-part8': [SKIP],
+}],  # 'gc_stress == True'
 ]

test/debugger/test-api.js

@@ -18,7 +18,7 @@ function receive(message) {
 class DebugWrapper {
   constructor() {
     // Message dictionary storing {id, message} pairs.
-    this.receivedMessages = {};
+    this.receivedMessages = new Map();
 
     // Each message dispatched by the Debug wrapper is assigned a unique number
     // using nextMessageId.
@@ -29,15 +29,39 @@ class DebugWrapper {
 
     // TODO(jgruber): Determine which of these are still required and possible.
     // Debug events which can occur in the V8 JavaScript engine.
-    this.DebugEvent = { Break: 1
-                      , Exception: 2
-                      , NewFunction: 3
-                      , BeforeCompile: 4
-                      , AfterCompile: 5
-                      , CompileError: 6
-                      , AsyncTaskEvent: 7
+    this.DebugEvent = { Break: 1,
+                        Exception: 2,
+                        NewFunction: 3,
+                        BeforeCompile: 4,
+                        AfterCompile: 5,
+                        CompileError: 6,
+                        AsyncTaskEvent: 7
                       };
 
+    // The different types of steps.
+    this.StepAction = { StepOut: 0,
+                        StepNext: 1,
+                        StepIn: 2,
+                        StepFrame: 3,
+                      };
+
+    // A copy of the scope types from runtime-debug.cc.
+    // NOTE: these constants should be backward-compatible, so
+    // add new ones to the end of this list.
+    this.ScopeType = { Global:  0,
+                       Local:   1,
+                       With:    2,
+                       Closure: 3,
+                       Catch:   4,
+                       Block:   5,
+                       Script:  6,
+                       Eval:    7,
+                       Module:  8
+                     };
+
+    // Store the current script id so we can skip corresponding break events.
+    this.thisScriptId = %FunctionGetScriptId(receive);
+
     // Register as the active wrapper.
     assertTrue(activeWrapper === undefined);
     activeWrapper = this;
@@ -69,14 +93,15 @@ class DebugWrapper {
 
     const {msgid, msg} = this.createMessage(
         "Debugger.setBreakpoint",
-        { location : { scriptId : scriptid.toString()
-                     , lineNumber : loc.line
-                     , columnNumber : loc.column
+        { location : { scriptId : scriptid.toString(),
+                       lineNumber : loc.line,
+                       columnNumber : loc.column
                      }
         });
     this.sendMessage(msg);
 
-    const reply = this.receivedMessages[msgid];
+    const reply = this.takeReplyChecked(msgid);
+    assertTrue(reply.result !== undefined);
     const breakid = reply.result.breakpointId;
     assertTrue(breakid !== undefined);
 
@@ -87,7 +112,7 @@ class DebugWrapper {
     const {msgid, msg} = this.createMessage(
         "Debugger.removeBreakpoint", { breakpointId : breakid });
     this.sendMessage(msg);
-    assertTrue(this.receivedMessages[msgid] !== undefined);
+    this.takeReplyChecked(msgid);
   }
 
   // Returns the serialized result of the given expression. For example:
@@ -95,12 +120,12 @@ class DebugWrapper {
   evaluate(frameid, expression) {
     const {msgid, msg} = this.createMessage(
         "Debugger.evaluateOnCallFrame",
-        { callFrameId : frameid
-        , expression : expression
+        { callFrameId : frameid,
+          expression : expression
         });
     this.sendMessage(msg);
 
-    const reply = this.receivedMessages[msgid];
+    const reply = this.takeReplyChecked(msgid);
     return reply.result.result;
   }
 
@@ -117,7 +142,7 @@ class DebugWrapper {
       method: method,
       params: params,
     });
-    return {msgid: id, msg: msg};
+    return { msgid : id, msg: msg };
   }
 
   receiveMessage(message) {
@@ -125,7 +150,7 @@ class DebugWrapper {
 
     const parsedMessage = JSON.parse(message);
     if (parsedMessage.id !== undefined) {
-      this.receivedMessages[parsedMessage.id] = parsedMessage;
+      this.receivedMessages.set(parsedMessage.id, parsedMessage);
     }
 
     this.dispatchMessage(parsedMessage);
@@ -139,7 +164,44 @@ class DebugWrapper {
   sendMessageForMethodChecked(method) {
     const {msgid, msg} = this.createMessage(method);
     this.sendMessage(msg);
-    assertTrue(this.receivedMessages[msgid] !== undefined);
+    this.takeReplyChecked(msgid);
+  }
+
+  takeReplyChecked(msgid) {
+    const reply = this.receivedMessages.get(msgid);
+    assertTrue(reply !== undefined);
+    this.receivedMessages.delete(msgid);
+    return reply;
+  }
+
+  execStatePrepareStep(action) {
+    switch(action) {
+      case this.StepAction.StepOut: this.stepOut(); break;
+      case this.StepAction.StepNext: this.stepOver(); break;
+      case this.StepAction.StepIn: this.stepInto(); break;
+      default: %AbortJS("Unsupported StepAction"); break;
+    }
+  }
+
+  execStateScope(scope) {
+    // TODO(jgruber): Mapping
+    return { scopeType: () => scope.type,
+             scopeObject: () => scope.object
+           };
+  }
+
+  execStateFrame(frame) {
+    const scriptid = parseInt(frame.location.scriptId);
+    const line = frame.location.lineNumber;
+    const column = frame.location.columnNumber;
+    const loc = %ScriptLocationFromLine2(scriptid, line, column, 0);
+    const func = { name : () => frame.functionName };
+    return { sourceLineText : () => loc.sourceText,
+             functionName : () => frame.functionName,
+             func : () => func,
+             scopeCount : () => frame.scopeChain.length,
+             scope : (index) => this.execStateScope(frame.scopeChain[index])
+           };
   }
 
   // --- Message handlers. -----------------------------------------------------
@@ -156,15 +218,25 @@ class DebugWrapper {
   handleDebuggerPaused(message) {
     const params = message.params;
 
+    // Skip break events in this file.
+    if (params.callFrames[0].location.scriptId == this.thisScriptId) return;
+
     // TODO(jgruber): Arguments as needed.
-    let execState = { frames: params.callFrames };
-    this.invokeListener(this.DebugEvent.Break, execState);
+    let execState = { frames : params.callFrames,
+                      prepareStep : this.execStatePrepareStep.bind(this),
+                      frame : (index) => this.execStateFrame(
+                          index ? params.callFrames[index]
+                                : params.callFrames[0]),
+                      frameCount : () => params.callFrames.length
+                    };
+    let eventData = this.execStateFrame(params.callFrames[0]);
+    this.invokeListener(this.DebugEvent.Break, execState, eventData);
   }
 
   handleDebuggerScriptParsed(message) {
     const params = message.params;
-    let eventData = { scriptId : params.scriptId
-                    , eventType : this.DebugEvent.AfterCompile
+    let eventData = { scriptId : params.scriptId,
+                      eventType : this.DebugEvent.AfterCompile
                     }
 
     // TODO(jgruber): Arguments as needed. Still completely missing exec_state,
@@ -179,3 +251,13 @@ class DebugWrapper {
     }
   }
 }
+
+// Simulate the debug object generated by --expose-debug-as debug.
+var debug = { instance : undefined };
+Object.defineProperty(debug, 'Debug', { get: function() {
+  if (!debug.instance) {
+    debug.instance = new DebugWrapper();
+    debug.instance.enable();
+  }
+  return debug.instance;
+}});

test/mjsunit/mjsunit.status

@@ -59,10 +59,6 @@
   'es6/debug-promises/reject-with-undefined-reject': [FAIL],
   'es6/debug-promises/reject-with-invalid-reject': [FAIL],
 
-  # Issue 3660: Replacing activated TurboFan frames by unoptimized code does
-  # not work, but we expect it to not crash.
-  'debug-step-turbofan': [PASS, FAIL],
-
   # Issue 5587: The eval'ed code is piped through Ignition and fails when being
   # live edited. This needs investigation.
   'debug-liveedit-double-call': [SKIP],
@@ -209,7 +205,6 @@
   'regress/regress-4121': [SKIP],
   'compare-known-objects-slow': [SKIP],
   # Tests taking too long
-  'debug-stepout-scope-part8': [SKIP],
   'mirror-object': [SKIP],
   'packed-elements': [SKIP],
   'regress/regress-1122': [SKIP],