Part 2 for <rdar://problem/8492788>

Part 2 for <rdar://problem/8492788>
Adopt WKScrollbarPainterController

Reviewed by Beth Dakin.

Use header detection to define scrollbar painting controller #define.

Source/JavaScriptCore:

* DerivedSources.make:
* JavaScriptCore.xcodeproj/project.pbxproj:

Source/WebCore:

* WebCore.exp.in:
* platform/mac/ScrollAnimatorMac.h:
* platform/mac/ScrollbarThemeMac.h:
* platform/mac/WebCoreSystemInterface.h:
* platform/mac/WebCoreSystemInterface.mm:

Source/WebKit/mac:

* WebCoreSupport/WebSystemInterface.mm:
(InitWebCoreSystemInterface):

Source/WebKit2:

* WebProcess/WebCoreSupport/mac/WebSystemInterface.mm:
(InitWebCoreSystemInterface):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@77287 268f45cc-cd09-0410-ab3c-d52691b4dbfc