Add support for disabling CSS Properties at runtime

Tools/DumpRenderTree/chromium/TestRunner/src/WebPreferences.cpp

Index: Tools/DumpRenderTree/chromium/TestRunner/src/WebPreferences.cpp
diff --git a/Tools/DumpRenderTree/chromium/TestRunner/src/WebPreferences.cpp b/Tools/DumpRenderTree/chromium/TestRunner/src/WebPreferences.cpp
index 986bd9852f46c618cf602e914e95bb1f12c136a9..cb6c82683719a4aba0fae69b0700698d0729ed41 100644
--- a/Tools/DumpRenderTree/chromium/TestRunner/src/WebPreferences.cpp
+++ b/Tools/DumpRenderTree/chromium/TestRunner/src/WebPreferences.cpp
@@ -82,6 +82,7 @@ void WebPreferences::reset()
     authorAndUserStylesEnabled = true;
     defaultTextEncodingName = WebString::fromUTF8("ISO-8859-1");
     experimentalWebGLEnabled = false;
+    experimentalCSSExclusionsEnabled = true;
     experimentalCSSRegionsEnabled = true;
     experimentalCSSGridLayoutEnabled = false;
     javaEnabled = false;
@@ -154,6 +155,7 @@ void WebPreferences::applyTo(WebView* webView)
     settings->setDefaultTextEncodingName(defaultTextEncodingName);
     settings->setExperimentalWebGLEnabled(experimentalWebGLEnabled);
     WebRuntimeFeatures::enableCSSRegions(experimentalCSSRegionsEnabled);
+    WebRuntimeFeatures::enableCSSExclusions(experimentalCSSExclusionsEnabled);
     settings->setExperimentalCSSGridLayoutEnabled(experimentalCSSGridLayoutEnabled);
     settings->setExperimentalCSSCustomFilterEnabled(cssCustomFilterEnabled);
     settings->setJavaEnabled(javaEnabled);