Enforce MAX_TEXTURE_SIZE to be a power of two

This is implied by GLES2.0 spec section 3.7.1. There, the expression
"level zero through k" strongly suggests that k is expected to be an
integer, and it follows that MAX_TEXTURE_SIZE should be a power of two.
This holds in practice for almost all current implementations. Clarify
this interpretation of the spec by explicitly testing it.
Merge pull request #324 from NVIDIA/pot-max-texture-size

Enforce MAX_TEXTURE_SIZE to be a power of two
After discussion with ECMAScript committee, Uint8ClampedArray was changed to no longer inherit from Uint8Array. Firefox never implemented this, so web compatibility impact should be minimal, and there are good arguments for keeping the types distinct because they do have differing behavior. (The original motivation was to allow Uint8ClampedArray instances coming from CanvasRenderingContext2D.getImageData to be passed to APIs taking Uint8Array, but this can be done with no copies simply by creating a new view against the same ArrayBuffer.)

Removed the invalidated test from the 1.0.2 conformance suite and updated the test (incompatibly) in the top of tree conformance suite.
Merge pull request #325 from kenrussell/uint8clampedarray

After discussion with ECMAScript committee, Uint8ClampedArray was change...
Per discussion with Olli Etuaho on public_webgl, clarified failure cases in section "Packing Restrictions for Uniforms and Varyings".
Merge pull request #329 from kenrussell/packing

Per discussion with Olli Etuaho on public_webgl, clarified failure cases...
Per discussion on public_webgl, clarified that MAX_TEXTURE_SIZE must be a power of two.
Merge pull request #330 from kenrussell/npot

Per discussion on public_webgl, clarified that MAX_TEXTURE_SIZE must be ...
Extract test for huge arrays into separate tests.
Review feedback
After objections on public_webgl, removed recently-added "differences" section regarding MAX_TEXTURE_SIZE parameter, and clarified in test conformance/limits/gl-max-texture-dimensions.html where the power-of-two restriction comes from.
Merge pull request #331 from kenrussell/npot

After objections on public_webgl, removed recently-added "differences" s...
Restructured oes-element-index-uint.html to act as a regression test for a bug in ANGLE which has since been fixed.

The component tests under conformance/buffers/ were unaffected by this bug, so not modifying them.

Bug: https://github.com/KhronosGroup/WebGL/issues/328
Merge pull request #332 from kenrussell/dynamic-draw

Restructured oes-element-index-uint.html to act as a regression test for...
Fixed bug pointed out by Lane Roberts at Samsung where webgl-shared-resources.html was timing out when the extension was not supported.
Merge pull request #333 from kenrussell/shared-resources

Fixed bug pointed out by Lane Roberts at Samsung where webgl-shared-reso...
Undo changes to 1.0.2 version
All extensions are disabled when the WebGLRendering context is lost, with
the exception of WEBGL_lose_context. Include this in the section on
extensions, as well as the steps to perform in the case of a lost context.

Also update the WEBGL_lose_context extension spec to point out that
it is an exception to the rule.
Merge pull request #327 from dslomov-chromium/huge-array-tests

Extract test for huge arrays into separate tests.
Disabled extensions mark any WebGLObject instances they create as
invalid. Calling any method on a disabled extension generates
a INVALID_OPERATION error.