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>