[WebGL] Return meaningful information in WebGL context creation error message.
For example, vendor, renderer, driver version, etc.This
way a developer can gather data on what platforms the app 
fails to run. This needs changes on both blink and chromium.

Below steps are followed to implement this

1. Add basic headers in blink.
2. Add the necessary apis in chromium.
3. Start using this in WebglRenderingContxt.cpp.

This patch represents step-1 in this process.

BUG=412440

Review URL: https://codereview.chromium.org/640293002

git-svn-id: svn://svn.chromium.org/blink/trunk@184620 bbb929c8-8fbe-4397-9dbb-9b2b20218538