Revert 177827 "WebGL: Free temporary GPU resources held by inact..."

New assertions triggered on debug GPU bots. See Bug 391400.

> WebGL: Free temporary GPU resources held by inactive or hidden WebGL.
> 
> This CL applies Canvas 2D change in r165966 to WebGL
> 
> TEST=fast/canvas/webgl/webgl-composite-modes-tabswitching.html,
> DrawingBufferTest.verifySetIsHiddenProperlyAffectsMailboxes
> 
> BUG=391400
> 
> Review URL: https://codereview.chromium.org/251023004

TBR=dongseong.hwang@intel.com

Review URL: https://codereview.chromium.org/381113003

git-svn-id: svn://svn.chromium.org/blink/trunk@177854 bbb929c8-8fbe-4397-9dbb-9b2b20218538