Fix warnings_checker.dart handling of multitests

tests/language/try_catch_syntax_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 main() {
   testMissingCatch();
   testMissingTry();
   testDuplicateCatchVariable();
   testIllegalFinally();
   testIllegalCatch();
   testIllegalRethrow();
 }
 
 testMissingCatch() {
-  try { } // /// 01: compile-time error
+  try { } // //# 01: compile-time error
 }
 
 testMissingTry() {
-  on Exception catch (e) { } //                  /// 02: compile-time error
-  on Exception catch (e, trace) { } //           /// 03: compile-time error
-  finally { } //                                 /// 04: compile-time error
+  on Exception catch (e) { } //                  //# 02: compile-time error
+  on Exception catch (e, trace) { } //           //# 03: compile-time error
+  finally { } //                                 //# 04: compile-time error
 }
 
 testDuplicateCatchVariable() {
-  try { } on Exception catch (e, e) { } /// 05: compile-time error
+  try { } on Exception catch (e, e) { } //# 05: compile-time error
 }
 
 testIllegalFinally() {
-  try { } finally (e) { } /// 06: compile-time error
+  try { } finally (e) { } //# 06: compile-time error
 }
 
 testIllegalCatch() {
-  try { } catch () { } //             /// 07: compile-time error
-  try { } on MammaMia catch (e) { } /// 08: static type warning
-  try { } catch (var e) { } //        /// 09: compile-time error
-  try { } catch (final e) { } //      /// 10: compile-time error
-  try { } catch (int e) { } //        /// 11: compile-time error
-  try { } catch (final int e) { } //  /// 12: compile-time error
-  try { } catch ([e, s]) { } //       /// 13: compile-time error
-  try { } catch (e, [s]) { } //       /// 14: compile-time error
-  try { } catch (e, [s0, s1]) { } //  /// 15: compile-time error
+  try { } catch () { } //             //# 07: compile-time error
+  try { } on MammaMia catch (e) { } //# 08: static type warning
+  try { } catch (var e) { } //        //# 09: compile-time error
+  try { } catch (final e) { } //      //# 10: compile-time error
+  try { } catch (int e) { } //        //# 11: compile-time error
+  try { } catch (final int e) { } //  //# 12: compile-time error
+  try { } catch ([e, s]) { } //       //# 13: compile-time error
+  try { } catch (e, [s]) { } //       //# 14: compile-time error
+  try { } catch (e, [s0, s1]) { } //  //# 15: compile-time error
 }
 
 testIllegalRethrow() {
-  try { rethrow; } catch (e) { } //            /// 16: compile-time error
-  try { } catch (e) { } finally { rethrow; } /// 17: compile-time error
+  try { rethrow; } catch (e) { } //            //# 16: compile-time error
+  try { } catch (e) { } finally { rethrow; } //# 17: compile-time error
 }