I'm attaching a testcase that shows the issue. It takes a very pixelated small image of white/orange pixels and does a drawImage with a source width/height of 1. The whole canvas should be uniformly one color. It was previously thought that non-"high"/"default" interpolation qualities in CG would not bleed pixel data from the source, but this appears to not be the case.
The fix is to have the useSubImage portion of ImageCG be used all the time. Uploading this patch now.
Created attachment 89086 [details]
Created attachment 89092 [details]
Comment on attachment 89092 [details]
r=me if you replace the tabs in the test case with spaces
Committed r83521: <http://trac.webkit.org/changeset/83521>