Update WebGL ChromeOS expectation

Marks conformance/glsl/constructors/glsl-construct-bvec3.html as
expected to fail on ChromeOS VMs. This is actually only somewhat flaky,
but is flaking on a trybot and causing FindIt to be unhappy despite the
test being explicitly marked with RetryOnFailure.

Bug: 1136106
Change-Id: I93bbe07f5a259e39ed2dbdfc8f135e12a0488d41
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2469139
Auto-Submit: Brian Sheedy <bsheedy@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#817328}

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

@@ -733,7 +733,7 @@ crbug.com/1043953 [ chromeos ] conformance/textures/misc/texture-size-limit.html
 
 crbug.com/1081973 [ chromeos ] conformance/textures/misc/compressed-tex-image.html [ Failure ]
 
-crbug.com/1136106 [ chromeos-board-amd64-generic ] conformance/glsl/constructors/glsl-construct-bvec3.html [ RetryOnFailure ]
+crbug.com/1136106 [ chromeos-board-amd64-generic ] conformance/glsl/constructors/glsl-construct-bvec3.html [ Failure ]
 
 # ChromeOS: AMD
 crbug.com/995652 [ chromeos amd ] conformance/uniforms/out-of-bounds-uniform-array-access.html [ Skip ]