Make the "size" parameter a tuple in the canvas WPT generator config
This makes the size property hashable, which makes it possible to do
self._unique_param('size') to get the size of the canvases in a
variant grid and make sure all variant uses the same canvas size.
YAML doesn't support tuple natively, so the property needs to be
manually converted to a tuple.
Bug: 364549423
Change-Id: I55540ff39807b6af851d629008a50f257eeda645
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5894511
Reviewed-by: Andres Ricardo Perez andresrperez@chromium.org
Commit-Queue: Jean-Philippe Gravel jpgravel@chromium.org
Cr-Commit-Position: refs/heads/main@{#1361792}