Fix warnings_checker.dart handling of multitests

tests/language/try_catch_on_syntax_test.dart

Index: tests/language/try_catch_on_syntax_test.dart
diff --git a/tests/language/try_catch_on_syntax_test.dart b/tests/language/try_catch_on_syntax_test.dart
index 5c4ad351a2a5bd7dddede0db9d553071590c47f1..33335dad006eed4b2a1fb0c4200efa8f5c349944 100644
--- a/tests/language/try_catch_on_syntax_test.dart
+++ b/tests/language/try_catch_on_syntax_test.dart
@@ -15,11 +15,11 @@ void test1() {
   try {
     throw new MyException1();
   }
-  on on MyException2 catch (e) { } /// 02: compile-time error
-  catch MyException2 catch (e) { } /// 03: compile-time error
-  catch catch catch (e) { } /// 04: compile-time error
-  on (e) { } /// 05: compile-time error
-  catch MyException2 catch (e) { } /// 06: compile-time error
+  on on MyException2 catch (e) { } //# 02: compile-time error
+  catch MyException2 catch (e) { } //# 03: compile-time error
+  catch catch catch (e) { } //# 04: compile-time error
+  on (e) { } //# 05: compile-time error
+  catch MyException2 catch (e) { } //# 06: compile-time error
   on MyException2 catch (e) {
     foo = 1;
   } on MyException1 catch (e) {
@@ -27,7 +27,7 @@ void test1() {
   } on MyException catch (e) {
     foo = 3;
   }
-  on UndefinedClass /// 07: static type warning
+  on UndefinedClass //# 07: static type warning
   catch(e) { foo = 4; }
   Expect.equals(2, foo);
 }
@@ -37,8 +37,8 @@ testFinal() {
     throw "catch this!";
     } catch (e, s) {
       // Test that the error and stack trace variables are final.
-      e = null; // /// 10: runtime error
-      s = null; // /// 11: runtime error
+      e = null; // //# 10: runtime error
+      s = null; // //# 11: runtime error
     }
 }