Test WebGLPathTracer extreme case timing

[gkjohnson]

See if updating materials, lights, etc are taking too long. Cache the state if possible to avoid unnecessary updates. Possibly add options for disabling / enabling only certain options.

[gkjohnson]

Render targets will have to be always updated since we can't tell if they're changed or not.

[gkjohnson]

Remaining:

• Light data
• Material data

Save the buffer state for lights and materials and compare before returning the result.