[debugger] temporarily re-implement --expose-debug-as.

This is done out of courtesy for Node.js and will be
removed as soon as we branch for version 5.8.

R=jgruber@chromium.org

Review-Url: https://codereview.chromium.org/2636423002
Cr-Commit-Position: refs/heads/master@{#42437}

src/bootstrapper.cc

@@ -4196,6 +4196,26 @@ bool Genesis::InstallSpecialObjects(Handle<Context> native_context) {
     WasmJs::Install(isolate);
   }
 
+  // Expose the debug global object in global if a name for it is specified.
+  if (FLAG_expose_debug_as != NULL && strlen(FLAG_expose_debug_as) != 0) {
+    // If loading fails we just bail out without installing the
+    // debugger but without tanking the whole context.
+    Debug* debug = isolate->debug();
+    if (!debug->Load()) return true;
+    Handle<Context> debug_context = debug->debug_context();
+    // Set the security token for the debugger context to the same as
+    // the shell native context to allow calling between these (otherwise
+    // exposing debug global object doesn't make much sense).
+    debug_context->set_security_token(native_context->security_token());
+    Handle<String> debug_string =
+        factory->InternalizeUtf8String(FLAG_expose_debug_as);
+    uint32_t index;
+    if (debug_string->AsArrayIndex(&index)) return true;
+    Handle<Object> global_proxy(debug_context->global_proxy(), isolate);
+    JSObject::AddProperty(handle(native_context->global_proxy()), debug_string,
+                          global_proxy, DONT_ENUM);
+  }
+
   return true;
 }
 

src/flag-definitions.h

@@ -614,6 +614,7 @@ DEFINE_BOOL(script_streaming, true, "enable parsing on background")
 
 // bootstrapper.cc
 DEFINE_STRING(expose_natives_as, NULL, "expose natives in global object")
+DEFINE_STRING(expose_debug_as, NULL, "expose debug in global object")
 DEFINE_BOOL(expose_free_buffer, false, "expose freeBuffer extension")
 DEFINE_BOOL(expose_gc, false, "expose gc extension")
 DEFINE_STRING(expose_gc_as, NULL,