Fix leak with binding Framebuffers directly. Using BindFramebuffer(1) then GenFramebuffers would return 1. This leads to a memory leak and was something that was obscuring debugging a bug in my ReadPixels fix for ES3. This also fixes a bug where running the texture tests along produces some random failures. BUG=angleproject:1290 BUG=angleproject:1299 Change-Id: If11e8c743d2ddde725b12749ac012f670cd290e1 Reviewed-on: https://chromium-review.googlesource.com/324820 Reviewed-by: Geoff Lang <geofflang@chromium.org> Commit-Queue: Jamie Madill <jmadill@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org>