Oilpan: Remove most WillBe types from the code base

third_party/WebKit/Source/core/dom/DOMStringMap.idl

 /*
  * Copyright (C) 2010 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 10 matching lines @@
  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  * THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 // https://html.spec.whatwg.org/#the-domstringmap-interface
 
 [
     OverrideBuiltins,
     SetWrapperReferenceFrom=element,
-    WillBeGarbageCollected,
+    GarbageCollected,
 ] interface DOMStringMap {
     [ImplementedAs=item] getter DOMString (DOMString name);
     [RaisesException] setter void (DOMString name, DOMString value);
     deleter void (DOMString name);
 
     // FIXME: The indexed getter, setter and deleter are not in the
     // spec and simply converts the index to a string.
     [NotEnumerable] getter DOMString (unsigned long index);
     [RaisesException] setter void (unsigned long index, DOMString value);
     deleter void (unsigned long index);
 };