Interceptor maintenance:

dart/frog/leg/lib/string_helper.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.
 
 class StringMatch implements Match {
   const StringMatch(int this._start,
                     String this.str,
                     String this.pattern);
 
   int start() => _start;
@@ skipping 70 matching lines @@
       var quoter =
         new RegExpWrapper(@'[-[\]{}()*+?.,\\^$|#\s]', false, false, true).re;
       var quoted = JS('String', @'#.replace(#, "\\$&")', from, quoter);
       var re = new RegExpWrapper(quoted, false, false, true).re;
       return JS('String', @'#.replace(#, #)', receiver, re, to);
     }
   } else if (from is RegExp) {
     var re = new RegExpWrapper.fromRegExp(from, true).re;
     return JS('String', @'#.replace(#, #)', receiver, re, to);
   } else {
+    checkNull(from);
     // TODO(floitsch): implement generic String.replace (with patterns).
     throw "StringImplementation.replaceAll(Pattern) UNIMPLEMENTED";
   }
 }
 
 stringReplaceFirstUnchecked(receiver, from, to) {
   if (from is String) {
     return JS('String', @'#.replace(#, #)', receiver, from, to);
   } else if (from is RegExp) {
     var re = new RegExpWrapper.fromRegExp(from, false).re;
     return JS('String', @'#.replace(#, #)', receiver, re, to);
   } else {
+    checkNull(from);
     // TODO(floitsch): implement generic String.replace (with patterns).
     throw "StringImplementation.replace(Pattern) UNIMPLEMENTED";
   }
 }
 
 stringSplitUnchecked(receiver, pattern) {
   if (pattern is String) {
     return JS('List', @'#.split(#)', receiver, pattern);
   } else if (pattern is RegExp) {
     var re = new RegExpWrapper.fromRegExp(pattern, false).re;
     return JS('List', @'#.split(#)', receiver, re);
   } else {
     throw "StringImplementation.split(Pattern) UNIMPLEMENTED";
   }
 }