webgl/1.0.2/conformance/glsl/misc/shader-uniform-packing-restrictions.html is very slow in debug builds, frequently timing out. Some bots report that as failure for some reason. Locally, I saw it take 16 seconds, which would turn into much longer when running all tests with hyper-threading.
Marked as slow in r177273. This probably won't help the testers that report the test as failing instead of timing out, but we'll see.