Currently, mathsize is partially implemented in the MathML UA stylesheet and partially implemented in the MathML DOM classes using addPropertyToPresentationAttributeStyle.
Created attachment 365679 [details] Patch
Comment on attachment 365679 [details] Patch Attachment 365679 [details] did not pass mac-wk2-ews (mac-wk2): Output: https://webkit-queues.webkit.org/results/11610039 New failing tests: http/wpt/mediarecorder/MediaRecorder-AV-audio-video-dataavailable.html
Created attachment 365692 [details] Archive of layout-test-results from ews107 for mac-highsierra-wk2 The attached test failures were seen while running run-webkit-tests on the mac-wk2-ews. Bot: ews107 Port: mac-highsierra-wk2 Platform: Mac OS X 10.13.6
Committed r243371: <https://trac.webkit.org/changeset/243371>
<rdar://problem/49147869>