Tighten up a bunch of types in test.dart.

tools/testing/dart/status_expression.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.
 
 library status_expression;
 
 /**
  * Parse and evaluate expressions in a .status file for Dart and V8.
  * There are set expressions and Boolean expressions in a .status file.
  * The grammar is:
@@ skipping 154 matching lines @@
       ? left.evaluate(environment)
       : new Set<String>();
   String toString() => "($left if $right)";
 }
 
 class SetConstant implements SetExpression {
   String value;
 
   SetConstant(String v) : value = v.toLowerCase();
 
-  Set<String> evaluate(environment) => new Set<String>.from([value]);
+  Set<String> evaluate(environment) => [value].toSet();
   String toString() => value;
 }
 
 // An iterator that allows peeking at the current token.
 class Scanner {
   List<String> tokens;
   Iterator tokenIterator;
   String current;
 
   Scanner(this.tokens) {
@@ skipping 119 matching lines @@
             "Expected value in expression, got ${scanner.current}");
       }
       TermConstant right = new TermConstant(scanner.current);
       scanner.advance();
       return new Comparison(left, right, negate);
     } else {
       return new BooleanVariable(left);
     }
   }
 }