Implement <select> Popup Menu using PagePopup

public/web/WebRuntimeFeatures.h

Index: public/web/WebRuntimeFeatures.h
diff --git a/public/web/WebRuntimeFeatures.h b/public/web/WebRuntimeFeatures.h
index 6a3d1400bca96e83a03665bf15ccc8c97ed436bc..1b73a8d1e1a63e4de4c167b5fd06a5da7f85da69 100644
--- a/public/web/WebRuntimeFeatures.h
+++ b/public/web/WebRuntimeFeatures.h
@@ -148,6 +148,8 @@ public:
 
     BLINK_EXPORT static void enableReducedReferrerGranularity(bool);
 
+    BLINK_EXPORT static void enableHTMLPopupMenu(bool);

[tkent, 2014/12/17 01:06:21]

I don't think we need to add the public function.

The plan would be:
1. Land all of the new popup implementation.
2. Play with Canary which has enable-experimental-web-platform-features
3. Change the flag in RuntimeEnabledFeatures.in; experimental -> stable
4. When the above change is shipped as Stable channel, remove the old
implementation.

[keishi, 2014/12/22 05:03:54]

Done.

+
 private:
     WebRuntimeFeatures();
 };