If an SVG is used as a non-tiling background image and it does not take up the entire space of the element it is the background of, Debug builds always paint a red background behind the image, even when a different color is specified. The red background does not correct itself when you force a repaint.
I have attached a screenshot of Debug and Release builds, and a test case that shows the problem.
Created attachment 17997
Created attachment 17998 [details]
HTML of test
Created attachment 17999 [details]
SVG for test
Created attachment 95611 [details]
Problem is gone, adding Beths testcase to svg/as-image.
Comment on attachment 95611 [details]
OK. I suspect we could make the test case simpler. But this is OK too.
Landed in r87829.