Fix unhandled promise console message to show stack trace of a DOMException.

Source/bindings/core/v8/V8ThrowException.cpp

Index: Source/bindings/core/v8/V8ThrowException.cpp
diff --git a/Source/bindings/core/v8/V8ThrowException.cpp b/Source/bindings/core/v8/V8ThrowException.cpp
index 1ced492b43de1c9eabc15068ee4f18022184edef..92b4fc7e34d6b4594e8f9d7cbdf47b79dfb8539a 100644
--- a/Source/bindings/core/v8/V8ThrowException.cpp
+++ b/Source/bindings/core/v8/V8ThrowException.cpp
@@ -73,6 +73,7 @@ v8::Handle<v8::Value> V8ThrowException::createDOMException(int ec, const String&
     ASSERT(!error.IsEmpty());
     ASSERT(exception->IsObject());
     exception->ToObject()->SetAccessor(v8AtomicString(isolate, "stack"), domExceptionStackGetter, domExceptionStackSetter, error);
+    V8HiddenValue::setHiddenValue(isolate, exception->ToObject(), V8HiddenValue::error(isolate), error);
 
     return exception;
 }