Implement platform deleters per spec.

Source/core/storage/Storage.cpp

 /*
  * Copyright (C) 2008 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 60 matching lines @@
 {
     setItem(name, value, exceptionState);
     return true;
 }
 
 bool Storage::anonymousIndexedSetter(unsigned index, const AtomicString& value, ExceptionState& exceptionState)
 {
     return anonymousNamedSetter(AtomicString::number(index), value, exceptionState);
 }
 
-bool Storage::anonymousNamedDeleter(const AtomicString& name, ExceptionState& exceptionState)
+DeleteResult Storage::anonymousNamedDeleter(const AtomicString& name, ExceptionState& exceptionState)
 {
     bool found = contains(name, exceptionState);
-    if (!found || exceptionState.hadException())
-        return false;
+    if (!found)
+        return DeleteUnknownProperty;
+    if (exceptionState.hadException())
+        return DeleteReject;
     removeItem(name, exceptionState);
     if (exceptionState.hadException())
-        return false;
-    return true;
+        return DeleteReject;
+    return DeleteSuccess;
 }
 
-bool Storage::anonymousIndexedDeleter(unsigned index, ExceptionState& exceptionState)
+DeleteResult Storage::anonymousIndexedDeleter(unsigned index, ExceptionState& exceptionState)
 {
-    return anonymousNamedDeleter(AtomicString::number(index), exceptionState);
+    DeleteResult result = anonymousNamedDeleter(AtomicString::number(index), exceptionState);
+    return result == DeleteUnknownProperty ? DeleteSuccess : result;
 }
 
 void Storage::namedPropertyEnumerator(Vector<String>& names, ExceptionState& exceptionState)
 {
     unsigned length = this->length(exceptionState);
     if (exceptionState.hadException())
         return;
     names.resize(length);
     for (unsigned i = 0; i < length; ++i) {
         String key = this->key(i, exceptionState);
@@ skipping 11 matching lines @@
 {
     if (name == "length")
         return false;
     bool found = contains(name, exceptionState);
     if (exceptionState.hadException() || !found)
         return false;
     return true;
 }
 
 }