Let --js-flags work when Harmony is enabled in about:flags (reland)

chrome/renderer/chrome_render_process_observer.cc

Index: chrome/renderer/chrome_render_process_observer.cc
diff --git a/chrome/renderer/chrome_render_process_observer.cc b/chrome/renderer/chrome_render_process_observer.cc
index de375a704a770b4a43395ea7ba0a8933798db76c..b25d9b77b276fb804c99c18ae636ce8a3697ed56 100644
--- a/chrome/renderer/chrome_render_process_observer.cc
+++ b/chrome/renderer/chrome_render_process_observer.cc
@@ -264,6 +264,11 @@ ChromeRenderProcessObserver::ChromeRenderProcessObserver(
   if (command_line.HasSwitch(switches::kEnableShowModalDialog))
     WebRuntimeFeatures::enableShowModalDialog(true);
 
+  if (command_line.HasSwitch(switches::kJavaScriptHarmony)) {
+    std::string flag("--harmony");
+    v8::V8::SetFlagsFromString(flag.c_str(), static_cast<int>(flag.size()));
+  }
+
   RenderThread* thread = RenderThread::Get();
   resource_delegate_.reset(new RendererResourceDelegate());
   thread->SetResourceDispatcherDelegate(resource_delegate_.get());