Remove CSS_EXCLUSIONS compile flag and leftover code

Remove CSS_EXCLUSIONS compile flag and leftover code
https://bugs.webkit.org/show_bug.cgi?id=135175

Reviewed by Zoltan Horvath.

At this point, the CSS_EXCLUSIONS flag guards nothing but some useless
stubs. This removes the flag and the useless code.

.:
* Source/cmake/WebKitFeatures.cmake:
* Source/cmakeconfig.h.cmake:

Source/JavaScriptCore:
* Configurations/FeatureDefines.xcconfig:

Source/WebCore:
No new tests, just removing code.

* Configurations/FeatureDefines.xcconfig:
* bindings/generic/RuntimeEnabledFeatures.cpp:
(WebCore::RuntimeEnabledFeatures::RuntimeEnabledFeatures):
* bindings/generic/RuntimeEnabledFeatures.h:
(WebCore::RuntimeEnabledFeatures::setCSSExclusionsEnabled): Deleted.
(WebCore::RuntimeEnabledFeatures::cssExclusionsEnabled): Deleted.
* testing/InternalSettings.cpp:
(WebCore::InternalSettings::Backup::Backup):
(WebCore::InternalSettings::Backup::restoreTo):
(WebCore::InternalSettings::setCSSExclusionsEnabled): Deleted.
* testing/InternalSettings.h:
* testing/InternalSettings.idl:

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

Source/WebKit2:
* Configurations/FeatureDefines.xcconfig:

WebKitLibraries:
* win/tools/vsprops/FeatureDefines.props:
* win/tools/vsprops/FeatureDefinesCairo.props:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@171479 268f45cc-cd09-0410-ab3c-d52691b4dbfc