Checks that update-draws of bufferSubData are respected

PASS gl.getError() is gl.NO_ERROR
PASS gl.getError() is gl.NO_ERROR
PASS gl.getError() is gl.NO_ERROR
PASS gl.getError() is gl.NO_ERROR
PASS top-left of canvas should be green.
PASS bottom-left of canvas should be green.
PASS Top-right of canvas should be green.
PASS bottom-right of canvas should be green.
PASS successfullyParsed is true

TEST COMPLETE