Fix warnings_checker.dart handling of multitests

tests/language_strong/class_override_test.dart

Index: tests/language_strong/class_override_test.dart
diff --git a/tests/language_strong/class_override_test.dart b/tests/language_strong/class_override_test.dart
index 57b736029f3766e691744197a1f59c39eadb7470..b14101e61e4e8506792225be906ed2cbf36ef80f 100644
--- a/tests/language_strong/class_override_test.dart
+++ b/tests/language_strong/class_override_test.dart
@@ -10,14 +10,14 @@ class A {
 }
 
 class B extends A {
-  foo(a) {} // /// 00: static type warning
+  foo(a) {} // //# 00: static type warning
 }
 
 main() {
   B instance = new B();
   try {
     instance.foo();
-  } on NoSuchMethodError catch (error) { // /// 00: continued
+  } on NoSuchMethodError catch (error) { // //# 00: continued
   } finally {
   }
   print("Success");