Remove the Promises old implementation.

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 76cebb3530785d235f2b106e9a4e29bb1815a8fb..c6ebbcdc809304132da3fcf446a7d6b29be5127c 100644
--- a/Source/bindings/v8/V8Initializer.cpp
+++ b/Source/bindings/v8/V8Initializer.cpp
@@ -166,15 +166,12 @@ 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(isolate, false);
 }