Failing Windows Debug WebGL tests:

https://build.chromium.org/p/chromium.gpu.fyi/builders/Win7%20Debug%20%28NVIDIA%29/builds/13587

Seems to fail in and around:

[  FAILED  ] WebglConformance.conformance_renderbuffers_framebuffer_object_attachment (320392 ms)
[ RUN      ] WebglConformance.conformance_renderbuffers_framebuffer_state_restoration

BUG=angleproject:1244
This reverts commit d72c61c6.

Change-Id: Id84d6988bc1a3530d8dde4c36d18b735f3de06fc
Reviewed-on: https://chromium-review.googlesource.com/329621Reviewed-by: Jamie Madill <jmadill@chromium.org>