Revert of WebGL: Free temporary GPU resources held by inactive or hidden WebGL.

Revert of WebGL: Free temporary GPU resources held by inactive or hidden WebGL. (https://codereview.chromium.org/251023004/)

Reason for revert:
The following tests have become flaky after this change was committed:
ContextLost.WebGLContextLostFromGPUProcessExit 
WebglConformance.conformance_context_incorrect_context_object_behaviour

The flakiness was observed in debug builds on Win7 and Linux

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Blink&testType=webgl_conformance_tests&tests=WebglConformance.conformance_context_incorrect_context_object_behaviour

http://test-results.appspot.com/dashboards/flakiness_dashboard.html#group=%40ToT%20Blink&testType=context_lost_tests&tests=ContextLost.WebGLContextLostFromGPUProcessExit

Original issue's description:
> 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
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177827

[Justin Novosad, 2014-07-10 17:10:53]

Created Revert of WebGL: Free temporary GPU resources held by inactive or hidden
WebGL.

[commit-bot: I haz the power, 2014-07-10 17:11:04]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/junov@chromium.org/385663002/1

[commit-bot: I haz the power, 2014-07-10 17:11:04]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-07-10 17:11:10]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Justin Novosad, 2014-07-10 17:15:49]

On 2014/07/10 17:11:10, I haz the power (commit-bot) wrote:
> No LGTM from a valid reviewer yet. Only full committers are accepted.
> Even if an LGTM may have been provided, it was from a non-committer or
> a provisional committer, _not_ a full super star committer.
> See http://www.chromium.org/getting-involved/become-a-committer
> Note that this has nothing to do with OWNERS files.

Cancelling. kbr beat me to it: https://codereview.chromium.org/381113003