Make exception throwing more robust in V8 out-of-stack situations

Source/bindings/core/v8/V8ThrowException.cpp

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *     notice, this list of conditions and the following disclaimer in the
@@ skipping 52 matching lines @@
     if (ec == V8ReferenceError)
         return V8ThrowException::createReferenceError(isolate, sanitizedMessage);
 
     v8::Handle<v8::Object> sanitizedCreationContext = creationContext;
 
     // FIXME: Is the current context always the right choice?
     Frame* frame = toFrameIfNotDetached(creationContext->CreationContext());
     if (!frame || !BindingSecurity::shouldAllowAccessToFrame(isolate, frame, DoNotReportSecurityError))
         sanitizedCreationContext = isolate->GetCurrentContext()->Global();
 
+    v8::TryCatch tryCatch;
 
     RefPtrWillBeRawPtr<DOMException> domException = DOMException::create(ec, sanitizedMessage, unsanitizedMessage);
     v8::Handle<v8::Value> exception = toV8(domException.get(), sanitizedCreationContext, isolate);
 
-    if (exception.IsEmpty())
+    if (!exception.IsEmpty()) {
+        if (tryCatch.HasCaught())
+            return tryCatch.Exception();
         return v8Undefined();
+    }

[haraken, 2015/02/04 09:41:41]

I might be misunderstanding but why is this not like:

if (tryCatch.HasCaught()) {
  ASSERT(exception.IsEmpty());
  return tryCatch.Exception();
}
ASSERT(!exception.IsEmpty());

?

[Jens Widell, 2015/02/04 09:48:01]

Oups, this was meant to be "if (exception.IsEmpty())" still. The added negation
is a left-over from a slightly different change that I made and then decided
against, and failed to undo completely.

I have no reason to doubt those are accurate assertions. I'll change to that.

[Jens Widell, 2015/02/04 09:50:52]

Done.

 
     // Attach an Error object to the DOMException. This is then lazily used to get the stack value.
     v8::Handle<v8::Value> error = v8::Exception::Error(v8String(isolate, domException->message()));
     ASSERT(!error.IsEmpty());
     ASSERT(exception->IsObject());
     exception->ToObject(isolate)->SetAccessor(v8AtomicString(isolate, "stack"), domExceptionStackGetter, domExceptionStackSetter, error);
     V8HiddenValue::setHiddenValue(isolate, exception->ToObject(isolate), V8HiddenValue::error(isolate), error);
 
     return exception;
 }
@@ skipping 64 matching lines @@
 }
 
 v8::Handle<v8::Value> V8ThrowException::throwException(v8::Handle<v8::Value> exception, v8::Isolate* isolate)
 {
     if (!v8::V8::IsExecutionTerminating())
         isolate->ThrowException(exception);
     return v8::Undefined(isolate);
 }
 
 } // namespace blink