Don't expose private libraries with dart.library.X.

tests/language/library_env_test.dart

 // Copyright (c) 2015, 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';
 
 main() {
   const NOT_PRESENT = null;
 
   Expect.isTrue(const bool.fromEnvironment("dart.library.async"));
   Expect.isTrue(const bool.fromEnvironment("dart.library.collection"));
   Expect.isTrue(const bool.fromEnvironment("dart.library.convert"));
   Expect.isTrue(const bool.fromEnvironment("dart.library.core"));
   Expect.isTrue(const bool.fromEnvironment("dart.library.typed_data"));
+  Expect.isTrue(const bool.fromEnvironment("dart.library.developer"));
+
+  // Internal libraries should not be exposed.
+  Expect.equals(NOT_PRESENT,
+      const bool.fromEnvironment("dart.library._internal",
+          defaultValue: NOT_PRESENT));
 
 
   bool hasHtmlSupport;
   hasHtmlSupport = true;   /// has_html_support: ok
   hasHtmlSupport = false;  /// has_no_html_support: ok
 
   if (hasHtmlSupport != null) {
     bool expectedResult = hasHtmlSupport ? true : NOT_PRESENT;
 
     Expect.equals(expectedResult,
@@ skipping 14 matching lines @@
     Expect.equals(expectedResult,
         const bool.fromEnvironment("dart.library.web_sql",
             defaultValue: NOT_PRESENT));
   }
 
   bool hasIoSupport;
   hasIoSupport = true;   /// has_io_support: ok
   hasIoSupport = false;  /// has_no_io_support: ok
 
   if (hasIoSupport != null) {
-    bool expectedResult = hasIoSupport ? true : NOT_PRESENT;
-
-    Expect.equals(expectedResult,
+    // Dartium overrides 'dart.library.io' to return "false".
+    // We don't test for the non-existance, but just make sure that
+    // dart.library.io is not set to true.
+    Expect.equals(hasIoSupport,
         const bool.fromEnvironment("dart.library.io",
-            defaultValue: NOT_PRESENT));
-    Expect.equals(expectedResult,
-        const bool.fromEnvironment("dart.library.developer",
-            defaultValue: NOT_PRESENT));
+            defaultValue: false));
   }
 
   bool hasMirrorSupport;
   hasMirrorSupport = true;   /// has_mirror_support: ok
   hasMirrorSupport = false;  /// has_no_mirror_support: ok
 
   if (hasMirrorSupport != null) {
     bool expectedResult = hasMirrorSupport ? true : NOT_PRESENT;
 
     Expect.equals(expectedResult,
@@ skipping 11 matching lines @@
       const bool.fromEnvironment("dart.library.converT",
           defaultValue: NOT_PRESENT));
   Expect.equals(NOT_PRESENT,
       const bool.fromEnvironment("dart.library.",
           defaultValue: NOT_PRESENT));
   Expect.equals(NOT_PRESENT,
       const bool.fromEnvironment("dart.library.core ",
           defaultValue: NOT_PRESENT));
 
 }