Improve decoding of JS TypeError.

dart/tests/compiler/dart2js_native/type_error_decode_test.dart

Index: dart/tests/compiler/dart2js_native/type_error_decode_test.dart
diff --git a/dart/tests/compiler/dart2js_native/type_error_decode_test.dart b/dart/tests/compiler/dart2js_native/type_error_decode_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..3c9a8f0ace7c5a0d482559c2113ec25c52208170
--- /dev/null
+++ b/dart/tests/compiler/dart2js_native/type_error_decode_test.dart
@@ -0,0 +1,52 @@
+// Copyright (c) 2013, 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.
+
+library test.type_error_decode_test;
+
+import 'package:expect/expect.dart';
+
+import 'dart:_js_helper';
+
+class Foo {
+  var field;
+}
+
+isNullError(e, trace) {
+  print('$e\nTrace: $trace');
+  return e is NullError;
+}
+
+isJsNoSuchMethodError(e, trace) {
+  print('$e\nTrace: $trace');
+  return e is JsNoSuchMethodError;
+}
+
+expectThrows(f, check) {
+  try {
+    f();
+  } catch (e, trace) {
+    if (check(e, trace)) {
+      return;
+    }
+    throw 'Unexpected exception: $e\n$trace';
+  }
+  throw 'No exception thrown';
+}
+
+main() {
+  var x = null;
+  var z = new Object();
+  var v = new List(1)[0];
+  var s = "Cannot call method 'foo' of null";
+  var nul = null;
+  var f = new Foo();
+  // This should foil code analysis so the variables aren't inlined below.
+  [].forEach((y) => f.field = nul = s = x = z = v = y);
+  expectThrows(() => x.fisk(), isNullError);
+  expectThrows(() => v.fisk(), isNullError);
+  expectThrows(() => z.fisk(), isJsNoSuchMethodError);
+  expectThrows(() => s.fisk(), isJsNoSuchMethodError);
+  expectThrows(() => null(), isNullError);
+  expectThrows(() => f.field(), isNullError);
+}