Fix bug #4593 (Wrap text in context menus & HTML main menus) -- see bug
thread for all the gory details. This fix preserves the current layout
(where label & shortcut are not two strictly separated columns), but the
downside is it may not work in other browsers.

May want to revisit later for that reason, but in the meantime this will
improve the Linux build (which has no native menubar yet).
Merge pull request #5580 from adobe/pflynn/html-menu-wrap

Fix bug #4593 (Text wrap in context menus & HTML main menus)