using proper types for webkit variants, see #16329

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76743 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

git cherry-pick 1a5b712
Conflicts:
  src/osx/webview_webkit.mm
resolving cherry-pick merge conflicts
Merge pull request #9 from smanders/osx_fix

osx fix