Standardize WinCairo conditionalized code under PLATFORM macro.

Standardize WinCairo conditionalized code under PLATFORM macro.
https://bugs.webkit.org/show_bug.cgi?id=64377

Reviewed by Maciej Stachowiak.

Source/JavaScriptCore:

* wtf/Platform.h: Update to use PLATFORM(WIN_CAIRO) for tests.

Source/WebCore:

Update compile-time conditions that had previously used #ifdef
of WIN_CAIRO to consistently use PLATFORM(WIN_CAIRO).

* WebCore.vcproj/WebCoreCairo.vsprops: Remove redundant declaration
  of WIN_CAIRO.
* WebCore.vcproj/WebCoreDebugCairoCFLite.vsprops: Update to use
  the existing WinCairo.vsprops file.
* WebCorePrefix.h: Update for new WTF_PLATFORM_WIN_CAIRO define.
* config.h: Update to use PLATFORM(WIN_CAIRO).

Tools:

Update compile-time conditions that had previously used #ifdef
of WIN_CAIRO to consistently use PLATFORM(WIN_CAIRO).

* DumpRenderTree/config.h: Switch to PLATFORM(WIN_CAIRO)
* DumpRenderTree/win/DumpRenderTreeCairo.vsprops: Remove redundant
  define of WIN_CAIRO=1.
* DumpRenderTree/win/DumpRenderTreeDebugCairoCFLite.vsprops: Add
  WinCairo.vsprops to set (to match Release build).

WebKitLibraries:

* win/tools/vsprops/WinCairo.vsprops: Update to comply with PLATFORM
  macro definition (WTF_PLATFORM_WIN_CAIRO)

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@90940 268f45cc-cd09-0410-ab3c-d52691b4dbfc