Fix more lint style issues in runtime patches.

runtime/lib/internal_patch.dart

 // Copyright (c) 2013, 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.
 
+import 'dart:core' hide Symbol;
+
 @patch List makeListFixedLength(List growableList)
     native "Internal_makeListFixedLength";
 
 @patch List makeFixedListUnmodifiable(List fixedLengthList)
     native "Internal_makeFixedListUnmodifiable";
 
 class VMLibraryHooks {
   // Example: "dart:isolate _Timer._factory"
   static var timerFactory;
 
@@ skipping 41 matching lines @@
            i >= srcStart; i--, j--) {
         dst[j] = src[i];
       }
     } else {
       for (int i = srcStart, j = dstStart; i < srcStart + count; i++, j++) {
         dst[j] = src[i];
       }
     }
   }
 }