Fix warnings_checker.dart handling of multitests

tests/language_strong/redirecting_factory_default_values_test.dart

Index: tests/language_strong/redirecting_factory_default_values_test.dart
diff --git a/tests/language_strong/redirecting_factory_default_values_test.dart b/tests/language_strong/redirecting_factory_default_values_test.dart
index 152d2c73c5050d3aaeec146847a6a511e49731bd..b2fee51201da18fad18370eaa467d829f7fe238d 100644
--- a/tests/language_strong/redirecting_factory_default_values_test.dart
+++ b/tests/language_strong/redirecting_factory_default_values_test.dart
@@ -9,8 +9,8 @@ import "package:expect/expect.dart";
 class A {
   A(this.a, [this.b = 0]);
   factory A.f(a) = A;
-  factory A.g(a, [b = 0]) = A; // /// 01: compile-time error
-  factory A.h(a, {b: 0}) = A; // /// 02: compile-time error
+  factory A.g(a, [b = 0]) = A; // //# 01: compile-time error
+  factory A.h(a, {b: 0}) = A; // //# 02: compile-time error
 
  int a;
  int b;