More optimizations cleanup.

runtime/lib/string.dart

 // Copyright (c) 2011, 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.
 
 /**
  * [StringBase] contains common methods used by concrete String implementations,
  * e.g., OneByteString.
  */
 class StringBase {
 
@@ skipping 38 matching lines @@
   String concat(String other) native "String_concat";
 
   String toString() {
     return this;
   }
 
   bool operator ==(Object other) {
     if (this === other) {
       return true;
     }
-    if (!(other is String) ||
+    if ((other is !String) ||
         (this.length != other.length)) {
       // TODO(5413632): Compare hash codes when both are present.
       return false;
     }
     return this.compareTo(other) === 0;
   }
 
   int compareTo(String other) {
     int thisLength = this.length;
     int otherLength = other.length;
@@ skipping 444 matching lines @@
     for (int g in groups) {
       result.add(group(g));
     }
     return result;
   }
 
   final int _start;
   final String str;
   final String pattern;
 }