Additional fixes to zero_termination_test

tests/compiler/dart2js/zero_termination_test.dart

 // Copyright (c) 2015, 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.
 
 // A regression test for issue 22667.
 //
 // Makes sure that we don't print a '\0' character for files that are not
 // properly new-line terminated.
 library zero_termination_test;
 
@@ skipping 29 matching lines @@
 }
 
 void cleanup() {
   File outFile = new File(outFilePath);
   if (outFile.existsSync()) {
     outFile.deleteSync();
   }
 }
 
 Future launchDart2Js(args) {
-  String executable = Platform.executable;
-  String command = path.join(path.dirname(executable), 'dart2js');

[Siggi Cherem (dart-lang), 2016/08/12 20:26:37]

this was dead code.

   String dart2jsPath = path.normalize(
       path.join(path.fromUri(Platform.script),
         '../../../../pkg/compiler/lib/src/dart2js.dart'));
-  List allArgs = ['--package-root=${Platform.packageRoot}',
-       dart2jsPath]..addAll(args);
+  List allArgs = [];
+  if (Platform.packageRoot != null) {

[Siggi Cherem (dart-lang), 2016/08/12 20:26:37]

this addresses Bill's comments from the other CL.

[Bill Hesse, 2016/08/15 15:48:36]

Acknowledged.

+    allArgs.add('--package-root=${Platform.packageRoot}');
+  } else if (Platform.packageConfig != null) {
+    allArgs.add('--packages=${Platform.packageConfig}');
+  }
+  allArgs.add(dart2jsPath);
+  allArgs.addAll(args);
   return Process.run(Platform.executable, allArgs, stdoutEncoding: null);
 }
 
 void check(ProcessResult result) {
   Expect.notEquals(0, result.exitCode);
   List<int> stdout = result.stdout;
   String stdoutString = UTF8.decode(stdout);
   Expect.isTrue(stdoutString.contains("Error"));
   // Make sure the "499" from the last line is in the output.
   Expect.isTrue(stdoutString.contains("499"));
@@ skipping 41 matching lines @@
     await testHttp();
   } finally {
     await tempDir.delete(recursive:true);
   }
 }
 
 main() {
   asyncStart();
   runTests().whenComplete(asyncEnd);
 }