Add Canvas team as owners of canvas

Change-Id: I5eec0c769d43c51078d759f4f9765b8b3d792c92
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2490381Reviewed-by: Aaron Krajeski <aaronhk@chromium.org>
Commit-Queue: Fernando Serboncini <fserb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#819379}

third_party/blink/renderer/modules/canvas/OWNERS

 fserb@chromium.org
+aaronhk@chromium.org
+juanmihd@chromium.org
+yiyix@chromium.org
 # canvas, imagebitmap
 senorblanco@chromium.org
 # lowLatency

third_party/blink/renderer/platform/graphics/OWNERS

@@ -5,6 +5,7 @@ flackr@chromium.org
 fmalita@chromium.org
 fserb@chromium.org
 jbroman@chromium.org
+juanmihd@chromium.org
 kbr@chromium.org
 pdr@chromium.org
 schenney@chromium.org