Make explicit constant for num of CSSPropertyIDs

third_party/WebKit/Source/core/css/CSSPropertyIDTemplates.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 CSSPropertyIDTemplates_h
 #define CSSPropertyIDTemplates_h
 
 #include "core/CSSPropertyNames.h"
 #include "wtf/HashFunctions.h"
 #include "wtf/HashTraits.h"
 
 namespace WTF {
 template <>
 struct DefaultHash<blink::CSSPropertyID> {
   typedef IntHash<unsigned> Hash;
 };
 template <>
 struct HashTraits<blink::CSSPropertyID>
     : GenericHashTraits<blink::CSSPropertyID> {
   static const bool emptyValueIsZero = true;
   static void constructDeletedValue(blink::CSSPropertyID& slot, bool) {
-    slot =
-        static_cast<blink::CSSPropertyID>(blink::lastUnresolvedCSSProperty + 1);
+    slot = static_cast<blink::CSSPropertyID>(blink::numCSSPropertyIDs);
   }
   static bool isDeletedValue(blink::CSSPropertyID value) {
-    return value == (blink::lastUnresolvedCSSProperty + 1);
+    return value == blink::numCSSPropertyIDs;
   }
 };
 }  // namespace WTF
 
 #endif  // CSSPropertyIDTemplates_h