Move the ScriptForbiddenScope in TreeScope::adoptIfNeeded to the top of the function.

third_party/WebKit/Source/core/dom/TreeScope.cpp

 /*
  * Copyright (C) 2011 Google Inc. All Rights Reserved.
  * Copyright (C) 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 352 matching lines @@
             // Strict mode, names need to match exactly.
             if (anchor.name() == name)
                 return &anchor;
         }
     }
     return nullptr;
 }
 
 void TreeScope::adoptIfNeeded(Node& node)
 {
+    // Script is forbidden to protect against event handlers firing in the middle of rescoping
+    // in |didMoveToNewDocument| callbacks. See https://crbug.com/605766 and https://crbug.com/606651.
+    ScriptForbiddenScope forbidScript;
     DCHECK(this);
     DCHECK(!node.isDocumentNode());
     TreeScopeAdopter adopter(node, *this);
-    if (adopter.needsScopeChange()) {
-        ScriptForbiddenScope forbidScript;
+    if (adopter.needsScopeChange())
         adopter.execute();
-    }
 }
 
 Element* TreeScope::retarget(const Element& target) const
 {
     for (const Element* ancestor = ⌖ ancestor; ancestor = ancestor->shadowHost()) {
         if (this == ancestor->treeScope())
             return const_cast<Element*>(ancestor);
     }
     return nullptr;
 }
@@ skipping 142 matching lines @@
     visitor->trace(m_idTargetObserverRegistry);
     visitor->trace(m_selection);
     visitor->trace(m_elementsById);
     visitor->trace(m_imageMapsByName);
     visitor->trace(m_labelsByForAttribute);
     visitor->trace(m_scopedStyleResolver);
     visitor->trace(m_radioButtonGroupScope);
 }
 
 } // namespace blink