An object's outline is inset by 1 pixel if the -webkit-border-radius property is specified, even if the specified value is 0 and there is no border. See test case.
Created attachment 11967 [details]
This is caused by a missing return at the end of the CSS_PROP__WEBKIT_BORDER_BOTTOM_RIGHT_RADIUS case in CSSStyleSelector::applyProperty(), causing fallthrough to the CSS_PROP_OUTLINE_OFFSET case.
Created attachment 12034 [details]
Let me know if a regression test is needed.
Comment on attachment 12034 [details]
The policy is that all patches should come with a regression test unless it's really not feasible or there's no change in behavior.
I'll r+ this, but please land it with a test.
Created attachment 12040 [details]
Added pixel test.
Comment on attachment 12040 [details]
Landed in r18442.