Update WebGL expectations.

tests/WebGL-CTS-known-failures.txt

+Currently top of tree WebGL has a crashing test.
+Instead, use the WebGL 1.0.3 test suite at: https://www.khronos.org/registry/webgl/conformance-suites/1.0.3/webgl-conformance-tests.html
+Known WebGL 1.0.3 failures using Chrome Canary with top of tree ANGLE:
+
+conformance/glsl/misc/struct-equals.html: 3 tests failed
+conformance/glsl/misc/struct-specifiers-in-uniforms.html: 12 tests failed
+conformance/glsl/misc/ternary-operators-in-global-initializers.html: 12 tests failed
+
+Below is outdated, to be updated once the tests can run again:
+
 Known failures in the WebGL CTS, top of tree, using Chromium
 https://www.khronos.org/registry/webgl/sdk/tests/webgl-conformance-tests.html