Fix warnings_checker.dart handling of multitests

tests/language/checked_null_test.dart

Index: tests/language/checked_null_test.dart
diff --git a/tests/language/checked_null_test.dart b/tests/language/checked_null_test.dart
index 95df12b2e7c3be12bada1584e3c0e9f1544d71fb..36ffd7b7d966cc586065eefccd0b356de3f8f8ba 100644
--- a/tests/language/checked_null_test.dart
+++ b/tests/language/checked_null_test.dart
@@ -13,7 +13,7 @@ class A {
 }
 
 main() {
-  Expect.throws(bar); /// 01: continued
+  Expect.throws(bar); //# 01: continued
 }
 
 bar() {
@@ -21,5 +21,5 @@ bar() {
   // receiver type is a typedef. Some code in the dart2js backend were
   // not dealing correctly with typedefs and lead the compiler to
   // crash.
-  new A().a.foo(); /// 01: static type warning
+  new A().a.foo(); //# 01: static type warning
 }