Fold buffer access validation into extensions. We only need to perform vertex array buffer validation if the WebGL compatiblity extension is enabled and robust access is not available. Although sometimes the range checks are useful for determining undefined behaviour they are not required by the OpenGL spec. They also slow down state updates significantly. This migrates the OOR tests into specific WebGL tests. It also requires a change to a Chromium test on the passthrough decoder. Improves perf by about 10% in the Vulkan VBO state change test. Also fixes some robust resource access cases for D3D11. Bug: angleproject:3000 Change-Id: Ice37f38f01c2f27bf32ed55657a30e69d8508335 Reviewed-on: https://chromium-review.googlesource.com/c/1390362 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org>