Revert fix for type checking of void type, because some top level tests fail.

tests/language/void_type_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.
-// Dart test for type checks involving the void type.
-
-isCheckedMode() {
-  try {
-    var i = 1;
-    String s = i;
-    return false;
-  } catch(var e) {
-    return true;
-  }
-}
-
-void f() { return; }
-
-void f_null() { return null; }
-
-void f_1() { return 1; }
-
-void f_dyn_null() {
-  var x = null;
-  return x;
-}
-
-void f_dyn_1() {
-  var x = 1;
-  return x;
-}
-
-void f_f() { return f(); }
-
-void test(int n, void func(), bool must_get_error) {
-  // Test as closure call.
-  {
-    bool got_type_error = false;
-    try {
-      var x = func();
-    } catch (TypeError error) {
-      got_type_error = true;
-    }
-    // Never a type error in production mode.
-    if (isCheckedMode()) {
-      Expect.isTrue(got_type_error == must_get_error);
-    } else {
-      Expect.isFalse(got_type_error);
-    }
-  }
-  // Test as direct call.
-  {
-    bool got_type_error = false;
-    try {
-      var x;
-      switch (n) {
-        case 0: x = f(); break;
-        case 1: x = f_null(); break;
-        case 2: x = f_1(); break;
-        case 3: x = f_dyn_null(); break;
-        case 4: x = f_dyn_1(); break;
-        case 5: x = f_f(); break;
-      }
-    } catch (TypeError error) {
-      got_type_error = true;
-    }
-    // Never a type error in production mode.
-    if (isCheckedMode()) {
-      Expect.isTrue(got_type_error == must_get_error);
-    } else {
-      Expect.isFalse(got_type_error);
-    }
-  }
-}
-
-main() {
-  test(0, f, false);
-  test(1, f_null, false);
-  test(2, f_1, true);
-  test(3, f_dyn_null, false);
-  test(4, f_dyn_1, true);
-  test(5, f_f, false);
-}
-
-