Add support for the node net module.

frog/tests/frog/src/NodeTestHelper.dart

Index: frog/tests/frog/src/NodeTestHelper.dart
===================================================================
--- frog/tests/frog/src/NodeTestHelper.dart	(revision 3470)
+++ frog/tests/frog/src/NodeTestHelper.dart	(working copy)
@@ -6,6 +6,8 @@
 
 #import('unittest_node.dart');
 #import('../../../lib/node/node.dart');
+#import('../../../lib/node/child_process.dart');
+#import('../../../lib/node/path.dart');
 
 /**
  * Helper method to be able to run the test from:
@@ -38,14 +40,9 @@
   for (var arg in argv) {
     sb.add(' $arg');
   }
-  // print('exec ${sb.toString()}');
   final child = child_process.exec(sb.toString(), callback);
   if (stdinText != null) {
-    // Something I don't understand:
-    // can't call 'child.stdin.end() directly, have
-    // to store child.stdin in a WritableStream variable. 'var' won't do.
-    WritableStream stdin = child.stdin;
-    stdin.end(stdinText);
+    child.stdin.end(stdinText, 'utf8');
   }
   return child;
 }