USE(CONTENT_FILTERING) should be ENABLE(CONTENT_FILTERING)
https://bugs.webkit.org/show_bug.cgi?id=135439

Reviewed by Tim Horton.

We now support two different platform content filters, and will soon support a mock content filter (as part of
webkit.org/b/128858). This makes content filtering a feature of WebKit, not just an adoption of a third-party
library. ENABLE() is the correct macro to use for such a feature.

Source/JavaScriptCore:
* Configurations/FeatureDefines.xcconfig:

Source/WebCore:
* Configurations/FeatureDefines.xcconfig:
* WebCore.exp.in:
* loader/DocumentLoader.cpp:
(WebCore::DocumentLoader::finishedLoading):
(WebCore::DocumentLoader::responseReceived):
(WebCore::DocumentLoader::commitData):
(WebCore::DocumentLoader::dataReceived):
* loader/DocumentLoader.h:
* loader/FrameLoaderClient.h:
* platform/ContentFilter.h:
* platform/ios/ContentFilterIOS.mm:
* platform/mac/ContentFilterMac.mm:

Source/WebKit/mac:
* Configurations/FeatureDefines.xcconfig:

Source/WebKit2:
* Configurations/FeatureDefines.xcconfig:
* Shared/WebCoreArgumentCoders.h:
* UIProcess/WebFrameProxy.cpp:
(WebKit::WebFrameProxy::didStartProvisionalLoad):
* UIProcess/WebFrameProxy.h:
* UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::decidePolicyForNavigationAction):
* UIProcess/WebPageProxy.h:
* UIProcess/WebPageProxy.messages.in:
* WebProcess/WebCoreSupport/WebFrameLoaderClient.cpp:
* WebProcess/WebCoreSupport/WebFrameLoaderClient.h:

Source/WTF:
* wtf/Platform.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@171826 268f45cc-cd09-0410-ab3c-d52691b4dbfc