Suppress Win10 GPU pixel failure

Suppresses Pixel_WebGL_PremultipliedAlpha_False on Win10/Intel HD 630
configurations.

TBR=kbr@chromium.org

Bug: 997313
Change-Id: I9451e3f71d4e435cc0e0b6009e4d9ea41fb23657
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1769551Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#690129}

content/test/gpu/gpu_tests/test_expectations/pixel_expectations.txt

@@ -243,3 +243,6 @@ crbug.com/983600 [ mojave amd-0x6821 ] Pixel_CSSFilterEffects_NoOverlays [ Retry
 [ linux ] Pixel_CanvasLowLatencyWebGLSwapChain [ Skip ]
 [ mac ] Pixel_CanvasLowLatency2DSwapChain [ Skip ]
 [ mac ] Pixel_CanvasLowLatencyWebGLSwapChain [ Skip ]
+
+# Producing incorrect image on Win10 Intel HD 630 w/ 26.20.100.6912 drivers.
+crbug.com/997313 [ win intel-0x5912 ] Pixel_WebGL_PremultipliedAlpha_False [ Failure ]