Add [TypeChecking=Interface] to XSLTProcessor interface

Source/core/xml/XSLTProcessor.h

Index: Source/core/xml/XSLTProcessor.h
diff --git a/Source/core/xml/XSLTProcessor.h b/Source/core/xml/XSLTProcessor.h
index 638ed06ea5f062616e21888345896a67ceee0f2a..262d4cff9d41662b411dc9732c42734511777393 100644
--- a/Source/core/xml/XSLTProcessor.h
+++ b/Source/core/xml/XSLTProcessor.h
@@ -56,8 +56,7 @@ public:
     // DOM methods
     void importStylesheet(PassRefPtrWillBeRawPtr<Node> style)
     {
-        if (style)
-            m_stylesheetRootNode = style;
+        m_stylesheetRootNode = style;
     }
     PassRefPtrWillBeRawPtr<DocumentFragment> transformToFragment(Node* source, Document* ouputDoc);
     PassRefPtrWillBeRawPtr<Document> transformToDocument(Node* source);