Catch uncaught promise rejections from V8 and log to console.

Source/core/dom/ExecutionContext.cpp

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2012 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
@@ skipping 114 matching lines @@
     // Ensure all ActiveDOMObjects are suspended also newly created ones.
     if (m_activeDOMObjectsAreSuspended)
         object->suspend();
 }
 
 bool ExecutionContext::shouldSanitizeScriptError(const String& sourceURL, AccessControlStatus corsStatus)
 {
     return !(securityOrigin()->canRequest(completeURL(sourceURL)) || corsStatus == SharableCrossOrigin);
 }
 
-void ExecutionContext::reportException(PassRefPtrWillBeRawPtr<ErrorEvent> event, int scriptId, PassRefPtrWillBeRawPtr<ScriptCallStack> callStack, AccessControlStatus corsStatus)
+void ExecutionContext::reportException(PassRefPtrWillBeRawPtr<ErrorEvent> event, int scriptId, PassRefPtrWillBeRawPtr<ScriptCallStack> callStack, AccessControlStatus corsStatus, bool isPromiseReject)
 {
     RefPtrWillBeRawPtr<ErrorEvent> errorEvent = event;
     if (m_inDispatchErrorEvent) {
         if (!m_pendingExceptions)
             m_pendingExceptions = adoptPtrWillBeNoop(new WillBeHeapVector<OwnPtrWillBeMember<PendingException> >());
         m_pendingExceptions->append(adoptPtrWillBeNoop(new PendingException(errorEvent->messageForConsole(), errorEvent->lineno(), errorEvent->colno(), scriptId, errorEvent->filename(), callStack)));
         return;
     }
 
     // First report the original exception and only then all the nested ones.
-    if (!dispatchErrorEvent(errorEvent, corsStatus))
+    // FIXME: Do not dispatch uncaught Promise rejects until the window.onerror spec is finalized.
+    if (isPromiseReject || !dispatchErrorEvent(errorEvent, corsStatus))
         logExceptionToConsole(errorEvent->messageForConsole(), scriptId, errorEvent->filename(), errorEvent->lineno(), errorEvent->colno(), callStack);
 
     if (!m_pendingExceptions)
         return;
 
     for (size_t i = 0; i < m_pendingExceptions->size(); i++) {
         PendingException* e = m_pendingExceptions->at(i).get();
         logExceptionToConsole(e->m_errorMessage, e->m_scriptId, e->m_sourceURL, e->m_lineNumber, e->m_columnNumber, e->m_callStack);
     }
     m_pendingExceptions.clear();
@@ skipping 110 matching lines @@
 void ExecutionContext::trace(Visitor* visitor)
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_pendingExceptions);
     HeapSupplementable<ExecutionContext>::trace(visitor);
 #endif
     LifecycleContext<ExecutionContext>::trace(visitor);
 }
 
 } // namespace blink