WebGLCompat: Fix depth & stencil query results. getFramebufferAttachmentParameter returns incorrect result for framebuffers in an inconsistent state. BUG=angleproject:2281 Change-Id: Ifb83ecaf16c95bf1237b2c4f2684de6aa2d55c46 Reviewed-on: https://chromium-review.googlesource.com/823224 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>