Fixing bug 406671. Speed up nsWindowSH::GetProperty(). r+sr=peterv@propagandism.org, a=jonas@sicking.cc

dom/src/base/nsDOMClassInfo.cpp

@@ -4466,7 +4466,18 @@ nsWindowSH::GetProperty(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
     // child frame in nsWindowSH::NewResolve() (*vp will tell us if
     // that's the case). If *vp is a window object (i.e. a child
     // frame), return without doing a security check.
+    //
+    // Calling GetWrappedNativeOfJSObject() is not all that cheap, so
+    // only do that if the JSClass name is one that is likely to be a
+    // window object.
 
+    const char *name = JS_GET_CLASS(cx, JSVAL_TO_OBJECT(*vp))->name;
+
+    // The list of Window class names here need to be kept in sync
+    // with the actual class names!
+    if ((*name == 'W' && strcmp(name, "Window") == 0) ||
+        (*name == 'C' && strcmp(name, "ChromeWindow") == 0) ||
+        (*name == 'M' && strcmp(name, "ModalContentWindow") == 0)) {
       nsCOMPtr<nsIXPConnectWrappedNative> vpwrapper;
       sXPConnect->GetWrappedNativeOfJSObject(cx, JSVAL_TO_OBJECT(*vp),
                                              getter_AddRefs(vpwrapper));
@@ -4482,6 +4493,7 @@ nsWindowSH::GetProperty(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
         }
       }
     }
+  }
 
   return NS_OK;
 }