Make RegExp constructor non-const.

sdk/lib/_internal/compiler/implementation/dart2js.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.
 
 library dart2js;
 
 import 'dart:io';
 import 'dart:uri';
 import 'dart:utf';
 
@@ skipping 17 matching lines @@
 
 /**
  * Extract the parameter of an option.
  *
  * For example, in ['--out=fisk.js'] and ['-ohest.js'], the parameters
  * are ['fisk.js'] and ['hest.js'], respectively.
  */
 String extractParameter(String argument) {
   // m[0] is the entire match (which will be equal to argument). m[1]
   // is something like "-o" or "--out=", and m[2] is the parameter.
-  Match m = const RegExp('^(-[a-z]|--.+=)(.*)').firstMatch(argument);
+  Match m = new RegExp('^(-[a-z]|--.+=)(.*)').firstMatch(argument);
   if (m == null) helpAndFail('Error: Unknown option "$argument".');
   return m[2];
 }
 
 String extractPath(String argument) {
   String path = nativeToUriPath(extractParameter(argument));
   return path.endsWith("/") ? path : "$path/";
 }
 
 void parseCommandLine(List<OptionHandler> handlers, List<String> argv) {
@@ skipping 384 matching lines @@
     } catch (ignored) {
       print('Internal error: error while printing exception');
     }
     try {
       print(trace);
     } finally {
       exit(253); // 253 is recognized as a crash by our test scripts.
     }
   }
 }