Newly imported WebGL tests run the test in an iframe, and hide most results. So when a test fails, all we see is a FAIL. Comparing these to older versions, it looks like we can do better. See e.g. fast/canvas/webgl/angle-instanced-arrays.html vs. webgl/1.0.3/conformance/extensions/angle-instanced-arrays.html - the former actually prints the results.