A WebKit-specific CSS animation (-webkit-transition:) for change of 'color' attribute does not render to entirety of affected text when certain typefaces are used. In particular, Agenda and Hoefler Text present this problem; the majority of fonts are not affected.
In the presented test case, render issues occur at the top edge of ascenders, bottom edge of descenders, and the right edge of the "y" for text set in Hoefler Text.
Tested on WebKit nightly r35177 on 10.5; issue present with "strong" and "light" text antialiasing selected in System Preferences. Test case attached.
Created attachment 22313 [details]
Test case for bug 20060
Created attachment 22314 [details]
Incorrect rendering for bug 20060
Correct rendering would be a completely white image.
This is not specific to animation.
*** This bug has been marked as a duplicate of 6274 ***