Re-enable compositing/reflections/reflection-on-composited.html

The root cause of compositing/reflections/reflection-on-composited.html failing
with Vulkan SwiftShader has been fixed. This updates the test expectations
accordingly

TBR=backer@chromium.org
TEST=compositing/reflections/reflection-on-composited.html
TEST=vulkan_swiftshader_blink_web_tests

Bug: 979652
Change-Id: I2979d1018b81c0a3d406bd6a822c07c2eac09423
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1716618Reviewed-by: Jonathan Ross <jonross@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#680636}

third_party/blink/web_tests/FlagExpectations/use-vulkan=swiftshader

@@ -205,6 +205,3 @@ crbug.com/977289 css3/filters/blur-filter-page-scroll-self.html [ Skip ]
 crbug.com/977289 css3/filters/effect-reference-add-hw.html [ Skip ]
 crbug.com/977289 css3/filters/effect-reference-source-alpha-hw.html [ Skip ]
 crbug.com/977289 css3/filters/effect-reference-subregion-hidpi-hw.html [ Skip ]
-
-# Color issue in Reflection test
-crbug.com/979652 compositing/reflections/reflection-on-composited.html [ Skip ]