Add onerror handling for img/video loading.
Updates
Matrix Attribute Test

Add a conformance test that verifies matrix attribute locations do not clash with other shader attributes, regardless of their position in the attribute list.
Address feedback from Ken

- Alphabetically sorted 00_test_list.txt
- Replaced finishTest() with 'var successfullyParsed = true;'
Merge pull request #691 from RafaelCintron/matrixAttributes

Matrix Attribute Test
Remove onload arg from makeVideo.
Merge pull request #689 from zhenyao/onerror

Add onerror handling for img/video loading.