First pass at asynchronous input loading in dart2js.

tests/compiler/dart2js/no_duplicate_constructor_body2_test.dart

Index: tests/compiler/dart2js/no_duplicate_constructor_body2_test.dart
diff --git a/tests/compiler/dart2js/no_duplicate_constructor_body2_test.dart b/tests/compiler/dart2js/no_duplicate_constructor_body2_test.dart
index f2de6cf41564910146663bf010a88cce5102d346..1e9e95cb252be144f6fe9d39dfc987950c0a9c54 100644
--- a/tests/compiler/dart2js/no_duplicate_constructor_body2_test.dart
+++ b/tests/compiler/dart2js/no_duplicate_constructor_body2_test.dart
@@ -21,8 +21,9 @@ main() {
 """;
 
 main() {
-  String generated = compileAll(CODE);
-  RegExp regexp = new RegExp(r'A\$0: function');
-  Iterator<Match> matches = regexp.allMatches(generated).iterator;
-  checkNumberOfMatches(matches, 1);
+  compileAll(CODE).then((generated) {
+    RegExp regexp = new RegExp(r'A\$0: function');
+    Iterator<Match> matches = regexp.allMatches(generated).iterator;
+    checkNumberOfMatches(matches, 1);
+  });
 }