The patch for https://bugs.webkit.org/show_bug.cgi?id=39941 has removed the ConstructionType argument for the StyleElement constructor call in MathMLElement.cpp but there is no default for that argument. As such, you get a compile error when building MathML.
Created attachment 59097 [details] Patch to MathMLElement.cpp to fix the compile error.
Comment on attachment 59097 [details] Patch to MathMLElement.cpp to fix the compile error. Clearing flags on attachment: 59097 Committed r61493: <http://trac.webkit.org/changeset/61493>
All reviewed patches have been landed. Closing bug.