Handle some failing DocumentOrderedMap ID lookups across tree removals.

third_party/WebKit/Source/core/dom/DocumentOrderedMap.h

Index: third_party/WebKit/Source/core/dom/DocumentOrderedMap.h
diff --git a/third_party/WebKit/Source/core/dom/DocumentOrderedMap.h b/third_party/WebKit/Source/core/dom/DocumentOrderedMap.h
index 0877b713598c760ce52f3e8cc0a5a2d1a707a437..dcb1683fe210de8b5b7bf153de249c4f204ed1ef 100644
--- a/third_party/WebKit/Source/core/dom/DocumentOrderedMap.h
+++ b/third_party/WebKit/Source/core/dom/DocumentOrderedMap.h
@@ -44,11 +44,11 @@ namespace blink {
 class Element;
 class TreeScope;
 
-class DocumentOrderedMap : public NoBaseWillBeGarbageCollectedFinalized<DocumentOrderedMap> {
+class DocumentOrderedMap : public NoBaseWillBeGarbageCollected<DocumentOrderedMap> {
     USING_FAST_MALLOC_WILL_BE_REMOVED(DocumentOrderedMap);
+    DECLARE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(DocumentOrderedMap);
 public:
     static PassOwnPtrWillBeRawPtr<DocumentOrderedMap> create();
-    ~DocumentOrderedMap();
 
     void add(const AtomicString&, Element*);
     void remove(const AtomicString&, Element*);
@@ -65,7 +65,8 @@ public:
     DECLARE_TRACE();
 
 #if ENABLE(ASSERT)
-    void willRemoveId(const AtomicString&);
+    void enterTreeRemoveScope();

[esprehn, 2016/01/05 07:48:33]

put the class here, add an #elseif and define the class to be a no-op.

[sof, 2016/01/05 12:37:18]

Done.

+    void leaveTreeRemoveScope();
 #endif
 
 private:
@@ -93,7 +94,7 @@ private:
 
     mutable Map m_map;
 #if ENABLE(ASSERT)
-    AtomicString m_removingId;
+    int m_treeRemovalScopeLevel = 0;

[esprehn, 2016/01/05 07:48:33]

I would just use a static int

[sof, 2016/01/05 12:37:18]

Done.

 #endif
 };