Enable V8 Promises.

Source/bindings/v8/V8Initializer.cpp

Index: Source/bindings/v8/V8Initializer.cpp
diff --git a/Source/bindings/v8/V8Initializer.cpp b/Source/bindings/v8/V8Initializer.cpp
index deee16b2bc8b2bcedd5a21eaed8c54eea118a881..a68800319dba6e6aac0d97ed967ee50c5257aa88 100644
--- a/Source/bindings/v8/V8Initializer.cpp
+++ b/Source/bindings/v8/V8Initializer.cpp
@@ -166,12 +166,15 @@ static void timerTraceProfilerInMainThread(const char* name, int status)
 
 static void initializeV8Common(v8::Isolate* isolate)
 {
+    // FIXME: This is a temporary flags and should be removed soon.
+    const char promiseFlags[] = "--harmony-promises";
     v8::ResourceConstraints constraints;
     constraints.ConfigureDefaults(static_cast<uint64_t>(blink::Platform::current()->physicalMemoryMB()) << 20, static_cast<uint32_t>(blink::Platform::current()->virtualMemoryLimitMB()) << 20, static_cast<uint32_t>(blink::Platform::current()->numberOfProcessors()));
     v8::SetResourceConstraints(isolate, &constraints);
 
     v8::V8::AddGCPrologueCallback(V8GCController::gcPrologue);
     v8::V8::AddGCEpilogueCallback(V8GCController::gcEpilogue);
+    v8::V8::SetFlagsFromString(promiseFlags, strlen(promiseFlags));
 
     v8::Debug::SetLiveEditEnabled(false, isolate);
 }