<third_party/WebKit> Fix building with MacOSX10.10.sdk.

RenderThemeChromiumMac.mm:
There is no implicit conversion from int to NSControlSize anymore.

ScrollAnimatorMac.mm updated as done in WebKit:
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@164767 268f45cc-cd09-0410-ab3c-d52691b4dbfc

ScrollbarThemeMacOverlayAPI.mm updated as done in WebKit:
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@161397

 268f45cc-cd09-0410-ab3c-d52691b4dbfc

WebScrollbarTheme.mm:
Avoid compiler warning and error about comparing/passing different enums.

Change-Id: I6d9f864427a32192049792bb7395ae0abe1a07d6
Reviewed-by: Michael Bruning <michael.bruning@digia.com>
Reviewed-by: Andras Becsi <andras.becsi@digia.com>