Adds Junit tests in dartc back into test.py

compiler/javatests/com/google/dart/compiler/ast/DartToSourceVisitorTest.java

 // 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.
 
 package com.google.dart.compiler.ast;
 
 import com.google.common.base.Joiner;
 import com.google.dart.compiler.CompilerTestCase;
 
 /**
@@ skipping 82 matching lines @@
          "// unit testcode",
          "var m = {\"a\" : 1, \"b\" : 2, \"c\" : 3};",
          ""));
      same(Joiner.on("\n").join(
          "// unit testcode",
          "var m = <int>{\"a\" : 1, \"b\" : 2, \"c\" : 3};",
          ""));
    }
 
    private void same(String sourceCode) {
-     DartUnit unit = parseUnit("testcode", sourceCode);
+     // Some of the syntax we are testing is only valid in a system library
+     DartUnit unit = parseUnitAsSystemLibrary("testcode", sourceCode);
      String result = unit.toSource();
      assertEquals(sourceCode, result);
    }
 
    private void testClassMemeber(String stmt) {
      String boilerplated =
        "// unit testcode\n" +
        "class c {\n" +
        "\n" +
        ""+stmt+"" +
        "}\n" +
        "\n";
      same(boilerplated);
    }
 
    private void testStmt(String stmt) {
      String boilerplated =
        "  m() {\n" +
        "    "+stmt+";\n" +
        "  }\n";
      testClassMemeber(boilerplated);
    }
 }