Update scrollbar-layer-placement-negative-z-index-child expectation

The main expectation for scrollbar-layer-placement-negative-z-index-child has
been changed:

https://chromium-review.googlesource.com/c/chromium/src/+/1694249

However with the test running again it encounters a blurring related to using
GPU Raster. Updating the expectations for skia_renderer_gl_blink_web_tests to
account for this. We'll need the flag specific rebaseline.

TBR=backer@chromium.org
TEST=skia_renderer_gl_blink_web_tests

Bug: 954328
Change-Id: I0fb92ff7ad7d6f463a28a0d45ae83c7af211011e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1697305Reviewed-by: Jonathan Ross <jonross@chromium.org>
Reviewed-by: Jonathan Backer <backer@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#676525}

third_party/blink/web_tests/FlagExpectations/enable-gpu-rasterization

@@ -88,6 +88,7 @@ crbug.com/978605 compositing/masks/mask-with-removed-filters.html [ Skip ]
 # Tests fail even with a fuzzy pixel diff. They require a re-baseline.
 crbug.com/954328 compositing/fixed-background-after-style-recalc.html [ Failure ]
 crbug.com/954328 compositing/overflow/mask-with-filter.html [ Failure ]
+crbug.com/954328 compositing/overflow/scrollbar-layer-placement-negative-z-index-child.html [ Failure ]
 crbug.com/954328 css3/blending/background-blend-mode-crossfade-image-gradient.html [ Failure ]
 crbug.com/954328 css3/blending/background-blend-mode-default-value.html [ Failure ]
 crbug.com/954328 css3/blending/background-blend-mode-gradient-gradient.html [ Failure ]