Add a test for out-of-range constant indices failing compilation

ESSL 1.00 spec states that a constant index must generate a compilation
error if it is out of range. Test this with a variety of constant
expressions.
Added new conformance test for break and continue statements.
Update nested-loops-with-break-and-continue.html
Backport bug fix from pull request #803 to earlier conformance suite snapshots.
Merge pull request #810 from kenrussell/backport-null-error-return-values

Backport bug fix from pull request #803 to earlier conformance suite sna...
Test for taking a power of a small constant in an user-defined function

This very specific shader code seems to trigger a bug in the Direct3D
shader compiler.
Merge pull request #812 from NVIDIA/test-pow-of-constant-in-user-defined

Test for taking a power of a small constant in an user-defined function
Added new conformance test for break and continue statements.
Merge branch 'master' of https://github.com/sugoi1/WebGL
Merge branch 'master' of https://github.com/sugoi1/WebGL

Removed original changes made from github.
Merge branch 'master' of https://github.com/sugoi1/WebGL
Update nested-loops-with-break-and-continue.html
Changed nested-loops-with-break-and-continue test to 1.0.4
Indented the shader code
Merge pull request #807 from sugoi1/master

Added new conformance test for break and continue statements.
Move the proposed constant index out of range test to extras for now

This test requires large changes without that much real-world impact, so
it should not be a part of the initial WebGL 2.0 conformance suite.
Merge pull request #806 from NVIDIA/constant-index-out-of-range-test

Add a test for out-of-range constant indices failing compilation
Make tex-image-and-sub-image-2d-with-webgl-canvas-* cover TEXTURE_CUBE_MAP.