[idl-generator] enable generate Java and JS code with method args

This PR includes two commits.

First commit only contains unchanged copies from Chromium/WebKit. version info:
    - Chromium revision: 3d2865457d425c691eb14ddfbd66a774a793cd58
    - WebKit revision: adfaa7e06fafd9c57a4b019fbef0950b185c4d87 (from svn revision 181697)
    - Tag: 39.0.2151.4
    - Last Commit in Chromium: b3038b5483c9601e64f05b3eb23e1a1f5b11e5ce

Second commit contains all changes to enable generation for xwalk extension:
    1. Add templates for generating java and js of Crosswalk Extension
    2. Change generator scripts to adapt extension
    3. Add script for utilizing generator scripts
    4. Add an example showing how to use generator