WTF: Support enums in DefaultHash and HashTraits by casting to integral types.

third_party/WebKit/Source/wtf/HashFunctions.h

Index: third_party/WebKit/Source/wtf/HashFunctions.h
diff --git a/third_party/WebKit/Source/wtf/HashFunctions.h b/third_party/WebKit/Source/wtf/HashFunctions.h
index c3d90d02655a162d8249f943f79fab200715aa95..207c409a0d8583e43e9ba274822a87f95030c27c 100644
--- a/third_party/WebKit/Source/wtf/HashFunctions.h
+++ b/third_party/WebKit/Source/wtf/HashFunctions.h
@@ -198,21 +198,23 @@ struct DefaultHash;
 
 // Actual implementation of DefaultHash.
 //
-// The case of |isIntegral| == false is not implemented. If you see a compile
-// error saying DefaultHashImpl<T, false> is not defined, that's because the
-// default hash functions for T are not defined. You need to implement them
+// The case of |isIntegralOrEnum| == false is not implemented. If you see a
+// compile error saying DefaultHashImpl<T, false> is not defined, that's because
+// the default hash functions for T are not defined. You need to implement them
 // yourself.
-template <typename T, bool isIntegral>
+template <typename T, bool isIntegralOrEnum>
 struct DefaultHashImpl;
 
 template <typename T>
 struct DefaultHashImpl<T, true> {
-  using Hash = IntHash<typename std::make_unsigned<T>::type>;
+  using Hash = IntHash<T>;
 };
 
 // Canonical implementation of DefaultHash.
 template <typename T>
-struct DefaultHash : DefaultHashImpl<T, std::is_integral<T>::value> {};
+struct DefaultHash
+    : DefaultHashImpl<T, std::is_integral<T>::value || std::is_enum<T>::value> {
+};
 
 // Specializations of DefaultHash follow.
 template <>