Improve Dart Debugger performance and robustness by creating Dart wrappers using the standard SetNa…

LayoutTests/dart/inspector/scope-variables.dart

 import 'dart:core' as core; // import with prefix so global dart:core fields don't appear in scope chain.
 import 'dart:html' as html; // import with prefix so global dart:html fields don't appear in scope chain.
 
 main() {
   html.window.onMessage.listen(handleMessage);
 }
 
 handleMessage(event) {
   if (event.data == 'fromJS') {
     handleMessage2(event);
@@ skipping 16 matching lines @@
 
   A(this.d) {}
 
   toString() {
     return "[Instance of A, d = $d]";
   }
 }
 
 var globalVariable = 'globalString';
 
+var globalMapVariable = {'foo': 'bar', 'baz': 42};
+
+var globalArrayVariable = [3, 1, 4, 1, 5, 9];
+
 String get throwingGetter {
   throw 'only the best reviews';
 }
+
+html.DivElement get exampleDivGetter => html.query("#example_div");