Minor improvement to File diagnostics

dart/tests/standalone/io/file_constructor_test.dart

+// 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.
+
+import 'dart:io';
+
+void main() {
+  bool developerMode = false;
+  assert(developerMode = true);
+  new File('blåbærgrød');

[Mads Ager (google), 2012/09/28 09:48:56]

This line and the next should be removed.

[ahe, 2012/09/28 10:42:57]

Why?

[Mads Ager (google), 2012/09/28 11:05:42]

I was thinking that it was redundant because of all the other tests that we have
that only work if the File constructor with a string works. But you are right
that this is a good unit test of only the constructor so feel free to keep.

+  new File('foo.txt');
+  try {
+    new File(null);
+    Expect.fail('ArgumentError expected.');
+  } on ArgumentError catch(e) {
+    // Expected.
+  }
+  try {
+    new File(1);
+    Expect.fail('Error expected.');
+  } on ArgumentError catch(e) {
+    if (developerMode) throw;
+  } on TypeError catch(e) {
+    if (!developerMode) throw;
+  }
+}