Remove Expect from core library.

tests/language/number_syntax_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.
 
+import "package:expect/expect.dart";
+
 class NumberSyntaxTest {
 
   static void testMain() {
     testShortDoubleSyntax();
     testDotSelectorSyntax();
   }
 
   static void testShortDoubleSyntax() {
     Expect.equals(0.0, .0);
     Expect.equals(0.5, .5);
@@ skipping 33 matching lines @@
     // Exponent notation.
     Expect.equals((0e0).toString(), 0e0.toString());
     Expect.equals((1e+1).toString(), 1e+1.toString());
     Expect.equals((2.1e-34).toString(), 2.1e-34.toString());
   }
 
 }
 main() {
   NumberSyntaxTest.testMain();
 }