Adding ASSERT for RuntimeEnabled feature XSLT

Source/core/xml/XSLImportRule.h

Index: Source/core/xml/XSLImportRule.h
diff --git a/Source/core/xml/XSLImportRule.h b/Source/core/xml/XSLImportRule.h
index e78fc08585a5881d309a091d0d98f2f00b8945da..954e046c8402c1cef314cc4a3266d7cb03fd0576 100644
--- a/Source/core/xml/XSLImportRule.h
+++ b/Source/core/xml/XSLImportRule.h
@@ -23,6 +23,7 @@
 #ifndef XSLImportRule_h
 #define XSLImportRule_h
 
+#include "RuntimeEnabledFeatures.h"
 #include "core/fetch/ResourcePtr.h"
 #include "core/fetch/StyleSheetResourceClient.h"
 #include "core/xml/XSLStyleSheet.h"
@@ -37,6 +38,7 @@ class XSLImportRule : private StyleSheetResourceClient {
 public:
     static PassOwnPtr<XSLImportRule> create(XSLStyleSheet* parentSheet, const String& href)
     {
+        ASSERT(RuntimeEnabledFeatures::xsltEnabled());
         return adoptPtr(new XSLImportRule(parentSheet, href));
     }