Add move constructor and assignment operator to RefPtr class

Source/wtf/text/AtomicString.h

Index: Source/wtf/text/AtomicString.h
diff --git a/Source/wtf/text/AtomicString.h b/Source/wtf/text/AtomicString.h
index 8983dcdced2527b02b55891b3c4724cf3ac5de15..447069d2df73e724c3636e50e3a1ac8232161db3 100644
--- a/Source/wtf/text/AtomicString.h
+++ b/Source/wtf/text/AtomicString.h
@@ -69,17 +69,6 @@ public:
         COMPILE_ASSERT((charactersCount - 1 <= ((unsigned(~0) - sizeof(StringImpl)) / sizeof(LChar))), AtomicStringFromLiteralCannotOverflow);
     }
 
-#if COMPILER_SUPPORTS(CXX_RVALUE_REFERENCES)
-    // We have to declare the copy constructor and copy assignment operator as well, otherwise
-    // they'll be implicitly deleted by adding the move constructor and move assignment operator.
-    // FIXME: Instead of explicitly casting to String&& here, we should use std::move, but that requires us to
-    // have a standard library that supports move semantics.
-    AtomicString(const AtomicString& other) : m_string(other.m_string) { }
-    AtomicString(AtomicString&& other) : m_string(static_cast<String&&>(other.m_string)) { }
-    AtomicString& operator=(const AtomicString& other) { m_string = other.m_string; return *this; }
-    AtomicString& operator=(AtomicString&& other) { m_string = static_cast<String&&>(other.m_string); return *this; }
-#endif
-
     // Hash table deleted values, which are only constructed and never copied or destroyed.
     AtomicString(WTF::HashTableDeletedValueType) : m_string(WTF::HashTableDeletedValue) { }
     bool isHashTableDeletedValue() const { return m_string.isHashTableDeletedValue(); }