Fix more signed/unsigned mismatches uncovered by MSVC /W3

Fix more signed/unsigned mismatches uncovered by MSVC /W3

Reviewed by John.

No regression tests possible.

* platform/network/cf/ResourceResponseCFNet.cpp:
(WebCore::filenameHasSaneExtension):
* platform/win/FontDataWin.cpp:
(WebCore::FontData::containsCharacters):
* platform/win/PlatformScrollBarSafari.cpp:
(WebCore::):
* platform/win/UniscribeController.cpp:
(WebCore::UniscribeController::advance):
(WebCore::UniscribeController::shapeAndPlaceItem):
* platform/win/WebCoreTextRenderer.cpp:
(WebCore::doDrawTextAtPoint):
* plugins/win/PluginDatabaseWin.cpp:
(WebCore::parseVersionString):
* plugins/win/PluginPackageWin.cpp:
(WebCore::splitString):
* plugins/win/PluginViewWin.cpp:
(WebCore::freeStringArray):
(WebCore::PluginViewWin::invalidateTimerFired):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@23877 268f45cc-cd09-0410-ab3c-d52691b4dbfc