Reapply "Refactor constant part." (r4958) with fixes.

frog/tests/leg/src/PrettyParameterTest.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.
 // Test that parameters keep their names in the output.
 
 #import("compiler_helper.dart");
 
 final String FOO = @"""
 void foo(var a, var b) {
 }
@@ skipping 57 matching lines @@
 """;
 
 main() {
   String generated = compile(FOO, 'foo');
   // TODO(ngeoffray): Use 'contains' when frog supports it.
   RegExp regexp = const RegExp(@"function\(a, b\) {");
   Expect.isTrue(regexp.hasMatch(generated));
 
   generated = compile(BAR, 'bar');
   regexp = const RegExp(@"function\(eval\$, \$\$eval\) {");
-  print(generated);
   Expect.isTrue(regexp.hasMatch(generated));
 
   generated = compile(PARAMETER_AND_TEMP, 'bar');
   regexp = const RegExp(@"print\$1\(t0\)");
   Expect.isTrue(regexp.hasMatch(generated));
   // Check that the second 't0' got another name.
   regexp = const RegExp(@"print\$1\(t0_0\)");
   Expect.isTrue(regexp.hasMatch(generated));
 
   generated = compile(NO_LOCAL, 'foo');
   regexp = const RegExp("return baz");
   Expect.isTrue(regexp.hasMatch(generated));
-  regexp = const RegExp("baz = 2");
+  regexp = const RegExp(@"baz = \(2\)");
   Expect.isTrue(regexp.hasMatch(generated));
-  regexp = const RegExp("baz = 3");
+  regexp = const RegExp(@"baz = \(3\)");
   Expect.isTrue(regexp.hasMatch(generated));
   regexp = const RegExp("bar === true");
   Expect.isTrue(regexp.hasMatch(generated));
 
   generated = compile(MULTIPLE_PHIS_ONE_LOCAL, 'foo');
-  regexp = const RegExp("var a = 2;");
+  regexp = const RegExp(@"var a = \(2\);");
   Expect.isTrue(regexp.hasMatch(generated));
 
-  regexp = const RegExp("a = 2;");
+  regexp = const RegExp(@"a = \(2\);");
   Iterator matches = regexp.allMatches(generated).iterator();
   Expect.isTrue(matches.hasNext());
   matches.next();
   Expect.isFalse(matches.hasNext());
 
   generated = compile(PARAMETER_INIT, 'foo');
   regexp = const RegExp("var result = start;");
   Expect.isTrue(regexp.hasMatch(generated));
 }