Add support for horizontal mouse wheel messages in Windows Desktop Aura.

This is simply a matter of recognizing the WM_MOUSEHWHEEL message as a valid mouse wheel message.
Tested this on web pages with horizontal scrollbars and it works well.

BUG=332797
R=sky@chromium.org, sky

Review URL: https://codereview.chromium.org/140653006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@245651 0039d316-1c4b-4281-b951-d872f2087c98
gfx::Point EventSystemLocationFromNative(
    const base::NativeEvent& native_event) {
  return gfx::Point(0, 0);
}

gfx::Point EventSystemLocationFromNative(
    const base::NativeEvent& native_event) {
  return gfx::Point(0, 0);
}
