Rewrite negative const tests into a few multi tests.

tests/language/src/ConstInit2NegativeTest.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.
-// Check that initializer is expected after final variable declaration.
-
-class Point {
-  final x_;
-  final y_;
-  const Point(x, y) : x_ = x, y_ = y;
-  operator +(int x) { return x; }
-}
-
-class ConstInit2NegativeTest {
-  static final N = 1;                    // ok
-  static final O = 1 + 3;                // ok
-  static final P = const Point(0, 0);    // ok
-  static final Q = new Point(0, 0) + 1;  // Error: not a compile time const.
-
-  static testMain() {
-    Expect.equals(1, N);
-    Expect.equals(4, O);
-    Expect.equals(0, P.x_);
-    Expect.equals(0, Q.x_);
-  }
-}
-
-main() {
-  ConstInit2NegativeTest.testMain();
-}