Sharpen GL test skip condition for NVIDIA The skip condition for GLSLTest_ES3.VaryingStructNotInitializedInVertexShader is modified to not skip NVIDIA on windows. Bug: angleproject:3413 Change-Id: I126d9fa9e36c3b6c07abfd24bdaf6feb76ac4f6f Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1640208 Commit-Queue: Jamie Madill <jmadill@chromium.org> Reviewed-by: Jamie Madill <jmadill@chromium.org>