Adding bug 99620, since having proper operator spacing will help here. I suspect we will end up doing something similar as Gecko to get accurate ink/logical metrics and do width correction.

It looks like the issue here is very specific to the delimiter. In STIX, the stretchable delimiter is thicker with a very large left and right bearing. For us, this means that when we consider the stretchable delimiter as a possibility for drawing an operator we will always create a large amount of horizontal space for that operator. I think the fix here is to copy Gecko and ignore the stretchable delimiter.

Created attachment 215684 [details] Patch

Created attachment 215688 [details] Adjust the test to use ‖ instead of &DoubleVerticalLine;

Bug 123543 also changes the mo-stretch test so it might makes sense to create Mac baselines when both these patches have landed.

Comment on attachment 215688 [details] Adjust the test to use ‖ instead of &DoubleVerticalLine; Attachment 215688 [details] did not pass mac-wk2-ews (mac-wk2): Output: http://webkit-queues.appspot.com/results/19298017 New failing tests: mathml/presentation/mo-stretch.html

Created attachment 215693 [details] Archive of layout-test-results from webkit-ews-13 for mac-mountainlion-wk2 The attached test failures were seen while running run-webkit-tests on the mac-wk2-ews. Bot: webkit-ews-13 Port: mac-mountainlion-wk2 Platform: Mac OS X 10.8.5

Comment on attachment 215688 [details] Adjust the test to use ‖ instead of &DoubleVerticalLine; Attachment 215688 [details] did not pass mac-ews (mac): Output: http://webkit-queues.appspot.com/results/19358066 New failing tests: mathml/presentation/mo-stretch.html

Created attachment 215711 [details] Archive of layout-test-results from webkit-ews-05 for mac-mountainlion The attached test failures were seen while running run-webkit-tests on the mac-ews. Bot: webkit-ews-05 Port: mac-mountainlion Platform: Mac OS X 10.8.5

Tests fail for Mac because they need a rebaseline.

Martin can you grab the results from the layout-test-results in the attached archives and update your patch again?

Created attachment 215930 [details] Patch with Mac results from archive

Looks like tests are passing now. :)

Comment on attachment 215930 [details] Patch with Mac results from archive r=me

<rdar://problem/15394108>

Committed r158678: <http://trac.webkit.org/changeset/158678>

Re-opened since this is blocked by bug 123820

Created attachment 216503 [details] Uploading patch again to get new Mac results

Comment on attachment 216503 [details] Uploading patch again to get new Mac results Attachment 216503 [details] did not pass mac-wk2-ews (mac-wk2): Output: http://webkit-queues.appspot.com/results/22638963 New failing tests: mathml/presentation/mo-stretch.html

Created attachment 216504 [details] Archive of layout-test-results from webkit-ews-13 for mac-mountainlion-wk2 The attached test failures were seen while running run-webkit-tests on the mac-wk2-ews. Bot: webkit-ews-13 Port: mac-mountainlion-wk2 Platform: Mac OS X 10.8.5

Committed r159007: <http://trac.webkit.org/changeset/159007>