Fix analyzer tests when run in checked mode.

pkg/analyzer_cli/test/reporter_test.dart

Index: pkg/analyzer_cli/test/reporter_test.dart
diff --git a/pkg/analyzer_cli/test/reporter_test.dart b/pkg/analyzer_cli/test/reporter_test.dart
index 4fab7bd25ae74bec2cd585bd1d3249737507275a..358b570587ad3f24c9479635e5477e9f8b52c5b4 100644
--- a/pkg/analyzer_cli/test/reporter_test.dart
+++ b/pkg/analyzer_cli/test/reporter_test.dart
@@ -33,6 +33,7 @@ main() {
     when(options.hintsAreFatal).thenReturn(false);
     when(options.machineFormat).thenReturn(false);
     when(options.verbose).thenReturn(false);
+    when(options.color).thenReturn(false);
 
     var reporter = new ErrorFormatter(out, options, stats);