Add an ENABLE_NOSNIFF feature flag.
https://bugs.webkit.org/show_bug.cgi?id=109029

Reviewed by Jochen Eisinger.

This new flag will control the behavior of 'X-Content-Type-Options: nosniff'
when processing script and other resource types.

.:

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

Source/JavaScriptCore:

* Configurations/FeatureDefines.xcconfig:

Source/WebCore:

* Configurations/FeatureDefines.xcconfig:

Source/WebKit/chromium:

* features.gypi:

Source/WebKit/mac:

* Configurations/FeatureDefines.xcconfig:

Source/WebKit2:

* Configurations/FeatureDefines.xcconfig:

Tools:

* Scripts/webkitperl/FeatureList.pm:
* qmake/mkspecs/features/features.pri:

WebKitLibraries:

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


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@141985 268f45cc-cd09-0410-ab3c-d52691b4dbfc