Change int.fromEnvironment in VM to use same code as int.parse.

tests/corelib/int_from_environment_test.dart

Index: tests/corelib/int_from_environment_test.dart
diff --git a/tests/corelib/int_from_environment_test.dart b/tests/corelib/int_from_environment_test.dart
index f842fddb4c328530545477984ff4f4045f9b8ec9..f6033a5177f4e4f601be8d32324662a869543c51 100644
--- a/tests/corelib/int_from_environment_test.dart
+++ b/tests/corelib/int_from_environment_test.dart
@@ -1,7 +1,7 @@
 // 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.
-// SharedOptions=-Da=1 -Db=-12 -Dc=0x123 -Dd=-0x1234
+// SharedOptions=-Da=1 -Db=-12 -Dc=0x123 -Dd=-0x1234 -De=+0x112296 -Df=99999999999999999999
 
 import "package:expect/expect.dart";
 
@@ -10,4 +10,6 @@ main() {
   Expect.equals(-12, const int.fromEnvironment('b'));
   Expect.equals(0x123, const int.fromEnvironment('c'));
   Expect.equals(-0x1234, const int.fromEnvironment('d'));
+  Expect.equals(0x112296, const int.fromEnvironment('e'));
+  Expect.equals(99999999999999999999, const int.fromEnvironment('f'));
 }