cleanup patch generation to preseve comments and remove @patch

test/generated_sdk/lib/core/identical.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.core;
 
-@patch
+/**
+ * Check whether two references are to the same object.
+ */
 bool identical(Object a, Object b) {
   return Primitives.identicalImplementation(a, b);
 }
 
-@patch
+/**
+ * Returns the identity hash code of `object`.
+ *
+ * Returns the same value as `object.hashCode` if [object] has not overridden
+ * [Object.hashCode]. Returns the value that [Object.hashCode] would return
+ * on this object, even if `hashCode` has been overridden.
+ *
+ * This hash code is compatible with [identical].
+ */
 int identityHashCode(Object object) => objectHashCode(object);