RetryOnFailure for Pixel_WebGL test on Fuchsia

TBR: kbr@chromium.org
No-Try: True
Bug: 1136742
Change-Id: Id23c347a86f2fa838670adf37be141237311458f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2463995Reviewed-by: Kai Ninomiya <kainino@chromium.org>
Commit-Queue: Kai Ninomiya <kainino@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815783}

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

@@ -75,6 +75,7 @@ crbug.com/1115673 [ fuchsia no-use-skia-dawn ] Pixel_WebGLCopyImage [ Skip ]
 crbug.com/1115673 [ fuchsia ] Pixel_CanvasLowLatencyWebGLDrawImage [ Skip ]
 crbug.com/1115673 [ fuchsia ] Pixel_CanvasLowLatencyWebGLRoundedCorners [ Skip ]
 crbug.com/1115673 [ fuchsia ] Pixel_CanvasLowLatencyWebGLOccluded [ Skip ]
+crbug.com/1136742 [ fuchsia no-use-skia-dawn ] Pixel_WebGLTransparentGreenTriangle_NoAlpha_ImplicitClear [ RetryOnFailure ]
 
 # Tests running with SwiftShader are skipped on platforms where SwiftShader
 # isn't supported.