[Sheriff] Mark virtual/gpu-rasterization/images/2-comp.html as flaky

Flakes observed at https://ci.chromium.org/p/chromium/builders/ci/Win10%20Tests%20x64/43474

Bug: 1038139
Change-Id: I7c5ac70294f3a438d31c069c61689cc7ad185b7d
Tbr: xiaochengh@chromium.org
NoTry: True
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1982932Reviewed-by: Xiaocheng Hu <xiaochengh@chromium.org>
Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727643}

third_party/blink/web_tests/TestExpectations

@@ -6152,3 +6152,4 @@ crbug.com/1038037 [ Win ] virtual/gpu-rasterization/images/exif-orientation-css.
 crbug.com/1038037 [ Win ] virtual/gpu-rasterization/images/exif-orientation-none-css.html [ Pass Failure ]
 crbug.com/1037798 [ Win ] virtual/gpu-rasterization/images/exif-orientation-image-document.html [ Pass Failure ]
 crbug.com/1038091 [ Win ] virtual/gpu-rasterization/images/jpeg-yuv-image-decoding.html [ Pass Failure ]
+crbug.com/1038139 [ Win ] virtual/gpu-rasterization/images/2-comp.html [ Pass Failure ]