Add a WebGL2 test for TEX_IMMUTABLE_FORMAT.
Merge pull request #739 from dvander/tex-immutable-format

Add a WebGL2 test for TEXTURE_IMMUTABLE_FORMAT.
Make preserveDrawingBuffer test less confusing in small windows

When run the conformance test harness on mobile devices, the canvas/div
element patterns could previously line wrap and make the page look
confusing. Fix this.
Merge pull request #740 from NVIDIA/preservedrawingbuffer-test-improvement

Make preserveDrawingBuffer test less confusing in small windows
minor fixes
Merge pull request #741 from bjacob/minorfixes

minor fixes