Revert "Remove NullPointerException."

tests/language/null_access_error_test.dart

-// Copyright (c) 2011, 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.
-
-class NullAccessTest {
-
-  static void testNullVariable() {
-    int variable;
-    bool exceptionCaught = false;
-    bool wrongExceptionCaught = false;
-    try {
-      variable++;
-    } on NoSuchMethodError catch (ex) {
-      exceptionCaught = true;
-    } catch (ex) {
-      wrongExceptionCaught = true;
-    }
-    Expect.isTrue(exceptionCaught);
-    Expect.isFalse(wrongExceptionCaught);
-  }
-
-  static int helperFunction(int parameter) {
-    return parameter++;
-  }
-
-  static void testNullFunctionCall() {
-    int variable;
-    bool exceptionCaught = false;
-    bool wrongExceptionCaught = false;
-    try {
-      variable = helperFunction(variable);
-    } on NoSuchMethodError catch (ex) {
-      exceptionCaught = true;
-    } catch (ex) {
-      wrongExceptionCaught = true;
-    }
-    Expect.isTrue(exceptionCaught);
-    Expect.isFalse(wrongExceptionCaught);
-  }
-
-  static void testMain() {
-    testNullVariable();
-    testNullFunctionCall();
-  }
-}
-
-main() {
-  NullAccessTest.testMain();
-}