Second round of cleanups for new optional parameter semantics.

tests/compiler/dart2js/scanner_offset_length_test.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.
 
 #import('../../../lib/compiler/implementation/scanner/scannerlib.dart');
 #import('../../../lib/compiler/implementation/scanner/scanner_implementation.dart');
 
-Token scan(String text) => new StringScanner(text, true).tokenize();
+Token scan(String text) =>
+    new StringScanner(text, includeComments: true).tokenize();
 
 check(String text) {
   Token token = scan(text);
   while (token.kind != EOF_TOKEN) {
     Expect.equals(token.slowToString().length, token.slowCharCount);
 
     var start = token.charOffset;
     var end = token.charOffset + token.slowCharCount;
 
     Expect.isTrue(start < text.length,
@@ skipping 19 matching lines @@
 main() {
     check('foo'); // identifier
     check('\'\''); // empty string
     check('\'foo\''); // simple string
     check('\'\$foo\''); // interpolation, identifier
     check('\'\${foo}\''); // interpolation, expression
 
     check('//'); // single line comment
     check('/**/'); // multi line comment
 }