Merge 69148 - [V8] Add FileReader to active DOM map...

Merge 69148 - [V8] Add FileReader to active DOM map
https://bugs.webkit.org/show_bug.cgi?id=47205

Reviewed by Nate Chapin.

We need to have a custom FileReader V8 constructor in order to add object
into active DOM map to prevent it from GC-ed when it is still in-use.

* Android.v8bindings.mk:
* WebCore.gypi:
* bindings/scripts/CodeGeneratorV8.pm:
* bindings/v8/custom/V8FileReaderCustom.cpp: Added.
(WebCore::V8FileReader::constructorCallback):
* fileapi/FileReader.idl:

TBR=jianli@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=69158