Capture/Replay: Print context diff on failure when verbose When run with the --verbose flag, and a test fails because the context comparison fails, then print the unified diff between the JSON serialization of context that was captured and the context when it was replayed. Bug: angleproject:5715 Change-Id: I86210d96e5bbdf63f1ed663ddf8dfcb33764cbea Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2821535 Commit-Queue: Gert Wollny <gert.wollny@collabora.com> Reviewed-by: Cody Northrop <cnorthrop@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>