Enforce queries' new availability semantics.

Enforce queries' new availability semantics.

Queries' results do not become available until control returns to the
browser's main loop.

Tested for all query types with new and modified tests in the WebGL 2.0
conformance suite.

BUG=539727
Committed: https://crrev.com/787e71aee905d6bb1660097197d3e49cf91331b0
Cr-Commit-Position: refs/heads/master@{#354557}

[Ken Russell (switch to Gerrit), 2015-10-16 02:06:32]

kbr@chromium.org changed reviewers:
+ bajones@chromium.org, zmo@chromium.org

[Ken Russell (switch to Gerrit), 2015-10-16 02:06:33]

Please review. Thanks.

I decided not to try to share code between WebGLTimerQueryEXT and WebGLQuery.
The C++ constructs needed would have made the code more confusing.
(WebGLTimerQueryEXT uses the 64-bit query methods, while WebGLQuery uses the
32-bit unsigned int methods.)

Tested with the new tests in https://github.com/KhronosGroup/WebGL/pull/1264 .

Note to dyen: the bug I ran into earlier was actually in the test. Date.now()
doesn't update in an intuitive manner if you busy-loop for a while and then call
it again in your next requestAnimationFrame callback. Changing the tests to
retry the getQueryParameter call a fixed number of times fixed the problem.
Thanks for your help earlier today.

[Ken Russell (switch to Gerrit), 2015-10-16 02:06:41]

The CQ bit was checked by kbr@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-10-16 02:06:57]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1408803003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1408803003/1

[commit-bot: I haz the power, 2015-10-16 03:13:37]

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

[commit-bot: I haz the power, 2015-10-16 03:13:37]

Dry run: This issue passed the CQ dry run.

[bajones, 2015-10-16 18:18:18]

lgtm

[bajones, 2015-10-16 18:18:19]

lgtm

[Zhenyao Mo, 2015-10-16 18:25:05]

LGTM

[Ken Russell (switch to Gerrit), 2015-10-16 18:35:26]

The CQ bit was checked by kbr@chromium.org

[commit-bot: I haz the power, 2015-10-16 18:35:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1408803003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1408803003/1

[commit-bot: I haz the power, 2015-10-16 18:44:20]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-16 18:45:27]

Patchset 1 (id:??) landed as
https://crrev.com/787e71aee905d6bb1660097197d3e49cf91331b0
Cr-Commit-Position: refs/heads/master@{#354557}