Oilpan: Remove most WillBe types from the code base

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

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DocumentOrShadowRoot_h
 #define DocumentOrShadowRoot_h
 
 #include "core/dom/Document.h"
 #include "core/dom/shadow/ShadowRoot.h"
 
@@ skipping 24 matching lines @@
     static DOMSelection* getSelection(TreeScope& treeScope)
     {
         return treeScope.getSelection();
     }
 
     static Element* elementFromPoint(TreeScope& treeScope, int x, int y)
     {
         return treeScope.elementFromPoint(x, y);
     }
 
-    static WillBeHeapVector<RawPtrWillBeMember<Element>> elementsFromPoint(TreeScope& treeScope, int x, int y)
+    static HeapVector<Member<Element>> elementsFromPoint(TreeScope& treeScope, int x, int y)
     {
         return treeScope.elementsFromPoint(x, y);
     }
 };
 
 } // namespace blink
 
 #endif // DocumentOrShadowRoot_h