Fixes #179 -- compile error if editing files during server mode

test/report_test.dart

Index: test/report_test.dart
diff --git a/test/report_test.dart b/test/report_test.dart
index 6305aaeaffef7c34facf8b658063bfb30060b7c0..03a086509d1c01c55826fa505885538e3bb621b1 100644
--- a/test/report_test.dart
+++ b/test/report_test.dart
@@ -33,8 +33,9 @@ void main() {
       '''.replaceAll('\n          ', '\n'),
     };
     testChecker(files);
-    var reporter = new SummaryReporter();
-    testChecker(files, reporter: reporter);
+
+    SummaryReporter reporter;
+    testChecker(files, createReporter: (x) => reporter = new SummaryReporter(x));
 
     _verifySummary(GlobalSummary summary) {
       var mainLib = summary.loose['file:///main.dart'];