Rewriting layers panel 3d view using webgl.

Review URL: https://codereview.chromium.org/214553002

Review URL: https://codereview.chromium.org/214553002

git-svn-id: svn://svn.chromium.org/blink/trunk@171284 bbb929c8-8fbe-4397-9dbb-9b2b20218538