The capture/replay context differences may not be in each frame,
so if the test signals that comparisons fail, don't bail if the
context JSON files are not found for one frame, but continue the
search until all possibly captured frames have been checked

Bug: angleproject:5953
Change-Id: I8af34cc0fe4de5615fc43ef6c45915055546f507
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2891772
Commit-Queue: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>