Move the status file parser into its own package.

pkg/status_file/test/status_expression_test.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// Copyright (c) 2017, 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 "package:expect/expect.dart";
 
-import "../../tools/testing/dart/environment.dart";
-import "../../tools/testing/dart/status_expression.dart";
+import "package:status_file/environment.dart";
+import "package:status_file/src/expression.dart";
 
 class TestEnvironment implements Environment {
   final Map<String, String> _values;
 
   TestEnvironment(this._values);
 
+  void validate(String name, String value, List<String> errors) {
+    throw new UnimplementedError();
+  }
+
   /// Looks up the value of the variable with [name].
   String lookUp(String name) => _values[name];
 
   operator []=(String key, String value) => _values[key] = value;
 }
 
 main() {
   testExpression();
   testSyntaxError();
   testBoolean();
@@ skipping 90 matching lines @@
   Expect.isFalse(expression.evaluate(environment));
   environment["runtime"] = "chrome";
   Expect.isFalse(expression.evaluate(environment));
 
   environment["compiler"] = "dart2js";
   environment["runtime"] = "ie9";
   Expect.isFalse(expression.evaluate(environment));
   environment["runtime"] = "chrome";
   Expect.isTrue(expression.evaluate(environment));
 }