RFE: tool for capturing calls through WebGLRenderingContext for replay

In https://bugs.chromium.org/p/chromium/issues/detail?id=596774 it was pointed out that sometimes WebGL conformance tests expose driver bugs that need standalone OpenGL tests for best reproducibility. We should add some tooling that captures all the calls through the WebGLRenderingContext and prints them out in source code form that can be compiled into a C++ test case, in particular for inclusion in the drawElements tests. Either https://benvanik.github.io/WebGL-Inspector/ or https://github.com/3Dparallax/insight would be good candidate tools for implementing this.

Start by evaluating WebGL-Inspector and insight as candidate capture tools. Define how calls through WebGLRenderingContext should be emitted as compilable C++ source for inclusion in the drawElements tests; done means a captured WebGL conformance case can be reproduced as a standalone OpenGL test.

Written by the indexing model from the issue text.