Start working on unparse validation.

lib/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 60 matching lines @@
     new OptionHandler('--library-root=.+', (String argument) {
       String path = nativeToUriPath(extractParameter(argument));
       if (!path.endsWith("/")) path = "$path/";
       libraryRoot = cwd.resolve(path);
     }),
     new OptionHandler('--out=.+|-o.+', (String argument) {
       explicitOut = true;
       out = cwd.resolve(nativeToUriPath(extractParameter(argument)));
     }),
     new OptionHandler('--allow-mock-compilation', passThrough),
+    new OptionHandler('--unparse-validation', passThrough),
     new OptionHandler('--no-colors', (_) => colors.enabled = false),
     new OptionHandler('--enable[_-]checked[_-]mode|--checked|-c',
                       (_) => passThrough('--enable-checked-mode')),
     new OptionHandler(@'--help|-h|/\?|/h', (_) => wantHelp = true),
     // The following two options must come last.
     new OptionHandler('-.*', (String argument) {
       helpAndFail('Error: Unknown option "$argument".');
     }),
     new OptionHandler('.*', (String argument) {
       arguments.add(nativeToUriPath(argument));
@@ skipping 195 matching lines @@
     } catch (var ignored) {
       print('Internal error: error while printing exception');
     }
     try {
       print(trace);
     } finally {
       exit(253); // 253 is recognized as a crash by our test scripts.
     }
   }
 }