[Webgl-blink] Add test function to force fail the webgl-context.

In order to test whether the  GPU(Vendor,Renderer,Driver info)
is getting fetched properly when creating the context,
we need to provide a function to force fail the context on 
creation, which can be used by test-runner. 

This patch implements the forceNextWebGLContextCreationToFail.
Test-runner can use this further.

test-runner-cl which uses forceNextWebGLContextCreationToFail
@https://codereview.chromium.org/706193003/

BUG=412440

Review URL: https://codereview.chromium.org/703903002

git-svn-id: svn://svn.chromium.org/blink/trunk@185272 bbb929c8-8fbe-4397-9dbb-9b2b20218538