WebGL: Suppress flaky failure shaderbuiltinvar

WebGL conformance test deqp/functional/gles3/shaderbuiltinvar.html is
flaky on Android Qualcomm.

TBR: kbr@chromium.org
Bug: 946177
Change-Id: I436fc390bf1e41614385cb5882e7436f2f3245b5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1539127Reviewed-by: James Darpinian <jdarpinian@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: James Darpinian <jdarpinian@chromium.org>
Cr-Commit-Position: refs/heads/master@{#644590}

content/test/gpu/gpu_tests/webgl2_conformance_expectations.py

@@ -1343,6 +1343,8 @@ class WebGL2ConformanceExpectations(WebGLConformanceExpectations):
         ['android', 'qualcomm'], bug=906740)
     self.Fail('deqp/functional/gles3/shaderderivate_dfdy.html',
         ['android', 'qualcomm'], bug=906745)
+    self.Flaky('deqp/functional/gles3/shaderbuiltinvar.html',
+        ['android', 'qualcomm'], bug=946177)
 
     # Nvidia (Shield TV) failures
     self.Fail('conformance2/glsl3/array-complex-indexing.html',