Catch uncaught promise rejections from V8 and log to console.

Source/core/dom/ExecutionContext.cpp

Index: Source/core/dom/ExecutionContext.cpp
diff --git a/Source/core/dom/ExecutionContext.cpp b/Source/core/dom/ExecutionContext.cpp
index 4ec9a88c8031b8d3d83268850358998f581dc5d5..528a6a80de560d822c2f1b3525be692a367a9ea2 100644
--- a/Source/core/dom/ExecutionContext.cpp
+++ b/Source/core/dom/ExecutionContext.cpp
@@ -132,7 +132,7 @@ bool ExecutionContext::shouldSanitizeScriptError(const String& sourceURL, Access
     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) {
@@ -143,7 +143,8 @@ void ExecutionContext::reportException(PassRefPtrWillBeRawPtr<ErrorEvent> event,
     }
 
     // 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)