Fix crash in ScriptDebugServer::wrapCallFrames

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdlib.h>
 
 #include "src/v8.h"
 
 #include "src/ast.h"
 #include "src/base/platform/platform.h"
@@ skipping 1011 matching lines @@
   bool should_report_exception =
       ShouldReportException(&can_be_caught_externally, catchable_by_javascript);
   bool report_exception = catchable_by_javascript && should_report_exception;
   bool try_catch_needs_message =
       can_be_caught_externally && try_catch_handler()->capture_message_ &&
       !thread_local_top()->rethrowing_message_;
   bool bootstrapping = bootstrapper()->IsActive();
 
   thread_local_top()->rethrowing_message_ = false;
 
-  // Notify debugger of exception.
+  // Notify debugger of exception. Temporarily clear any scheduled_exception
+  // to allow evaluating JavaScript from the debug event handler.
   if (catchable_by_javascript) {
+    Object* saved_scheduled_exception = scheduled_exception();
+    clear_scheduled_exception();

[Yang, 2014/09/10 14:46:13]

Can we put this into OnThrow?

[aandrey, 2014/09/11 05:48:29]

Done.

     debug()->OnThrow(exception_handle, report_exception);
+    thread_local_top()->scheduled_exception_ = saved_scheduled_exception;
   }
 
   // Generate the message if required.
   if (report_exception || try_catch_needs_message) {
     MessageLocation potential_computed_location;
     if (location == NULL) {
       // If no location was specified we use a computed one instead.
       ComputeLocation(&potential_computed_location);
       location = &potential_computed_location;
     }
@@ skipping 1336 matching lines @@
   if (prev_ && prev_->Intercept(flag)) return true;
   // Then check whether this scope intercepts.
   if ((flag & intercept_mask_)) {
     intercepted_flags_ |= flag;
     return true;
   }
   return false;
 }
 
 } }  // namespace v8::internal