Cleaning out unneeded WebGL DebugRenderInfo finch experiment plumbing

Blink side CL: https://codereview.chromium.org/141863002/

BUG=335373
R=cdn@chromium.org, thakis@chromium.org, zmo@chromium.org

Review URL: https://codereview.chromium.org/142493003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247346 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247346