Created attachment 362977 [details]
reduced test case
See attached test case. Without the opacity property, the emoji is drawn normally. The bug can be reproduced in the latest build (r242083).
Transparency layer is not big enough. Is this about not getting the right glyph bounds?
Yeah I think this bug is the same as https://bugs.webkit.org/show_bug.cgi?id=6274
*** This bug has been marked as a duplicate of bug 6274 ***