Fix Context::declaration_context to account for script contexts.

R=rossberg@chromium.org
BUG=v8:3690
LOG=N

Review URL: https://codereview.chromium.org/715263003

Cr-Commit-Position: refs/heads/master@{#25303}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25303 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/contexts.cc

@@ -55,7 +55,8 @@ bool ScriptContextTable::Lookup(Handle<ScriptContextTable> table,
 
 Context* Context::declaration_context() {
   Context* current = this;
-  while (!current->IsFunctionContext() && !current->IsNativeContext()) {
+  while (!current->IsFunctionContext() && !current->IsNativeContext() &&
+         !current->IsScriptContext()) {
     current = current->previous();
     DCHECK(current->closure() == closure());
   }

test/cctest/test-debug.cc

@@ -7618,3 +7618,38 @@ TEST(DebugBreakOnExceptionInObserveCallback) {
   CHECK(CompileRun("callbackRan")->BooleanValue());
   CHECK_EQ(1, exception_event_counter);
 }
+
+
+static void DebugHarmonyScopingListener(
+    const v8::Debug::EventDetails& event_details) {
+  v8::DebugEvent event = event_details.GetEvent();
+  if (event != v8::Break) return;
+
+  int break_id = CcTest::i_isolate()->debug()->break_id();
+
+  char script[128];
+  i::Vector<char> script_vector(script, sizeof(script));
+  SNPrintF(script_vector, "%%GetFrameCount(%d)", break_id);
+  v8::Local<v8::Value> result = CompileRun(script);
+
+  CHECK_EQ(1, result->Int32Value());
+}
+
+
+TEST(DebugBreakInLexicalScopes) {
+  i::FLAG_harmony_scoping = true;
+  i::FLAG_allow_natives_syntax = true;
+
+  DebugLocalContext env;
+  v8::Isolate* isolate = env->GetIsolate();
+  v8::HandleScope scope(isolate);
+  v8::Debug::SetDebugEventListener(DebugHarmonyScopingListener);
+
+  CompileRun(
+      "'use strict';            \n"
+      "let x = 1;               \n");
+  CompileRun(
+      "'use strict';            \n"
+      "let y = 1;               \n"
+      "debugger                 \n");
+}