Created attachment 233524 [details] testcase (requires Cambria Math) Operator stretching via the OpenType MATH table has not been tested much on Windows. Gurpreet recently said that there are new assertion failures. She also gave screenshots in the past showing rendering issues and the best rendering was achieved with Cambria Math (installed by default on Win >= 7). I open the bug to address the issues.
Created attachment 233525 [details] Screenshot of the testcase (WebKitGTK+) @Brent/Gurpreet: I'd appreciate if you could do more Windows testing and help fixing possible bugs (at least the assertions mentioned).
Created attachment 233526 [details] Screenshot of the testcase (Gecko 31 Linux)
I'm closing this bug, assuming that the support works on the Windows port (it is implemented but I'm not sure someone really tested it). If not, feel free to reopen.