Drop [LegacyInterfaceTypeChecking] where trivial in core/

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

 /*
  * Copyright (C) 2011 Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 59 matching lines @@
 {
 #if !ENABLE(OILPAN)
     ASSERT(m_registrations.isEmpty());
 #endif
     if (!m_records.isEmpty())
         InspectorInstrumentation::didClearAllMutationRecords(m_callback->executionContext(), this);
 }
 
 void MutationObserver::observe(Node* node, const MutationObserverInit& observerInit, ExceptionState& exceptionState)
 {
-    if (!node) {
-        exceptionState.throwDOMException(NotFoundError, "The provided node was null.");
-        return;
-    }
+    ASSERT(node);
 
     MutationObserverOptions options = 0;
 
     if (observerInit.hasAttributeOldValue() && observerInit.attributeOldValue())
         options |= AttributeOldValue;
 
     HashSet<AtomicString> attributeFilter;
     if (observerInit.hasAttributeFilter()) {
         const Vector<String>& sequence = observerInit.attributeFilter();
         for (unsigned i = 0; i < sequence.size(); ++i)
@@ skipping 182 matching lines @@
 {
 #if ENABLE(OILPAN)
     visitor->trace(m_callback);
     visitor->trace(m_records);
     visitor->trace(m_registrations);
     visitor->trace(m_callback);
 #endif
 }
 
 } // namespace blink