reduce the size of texture for out of bound test to avoid possible failure on allocation of ArrayBuffer


Although the test works well with both release and debug build of latest Chrome on Windows(31.0.1606.0 (Developer Build 218220) ), it seems Chrome Canary in Windows(31.0.1605.1 (Official Build 218221) canary Aura)  may crash on failure of allocation of ArrayBuffer. Not sure if it there is some different setting on the size of ArrayBuffer in V8 for official Build.

It would be better to refine the test to avoid the failure on allocation of ArrayBuffer by reducing the size used for testing. This patch is verified using both the release/debug build from the latest chromium code and the Canary browser.