Fix warnings_checker.dart handling of multitests

tests/language_strong/async_switch_test.dart

Index: tests/language_strong/async_switch_test.dart
diff --git a/tests/language_strong/async_switch_test.dart b/tests/language_strong/async_switch_test.dart
index 1e37321117273282779f7889c288e3221af03f03..8fabeb68aeaf8b0fa69998683a6bde8979e9f848 100644
--- a/tests/language_strong/async_switch_test.dart
+++ b/tests/language_strong/async_switch_test.dart
@@ -16,7 +16,7 @@ foo1(a) async {
     case 2:
       k += a;
       return k+2;
-    default: k = 2; /// withDefault: ok
+    default: k = 2; //# withDefault: ok
   }
   return k;
 }
@@ -31,7 +31,7 @@ foo2(a) async {
     case 2:
       k += await a;
       return k+2;
-    default: k = 2; /// withDefault: ok
+    default: k = 2; //# withDefault: ok
   }
   return k;
 }
@@ -45,7 +45,7 @@ foo3(a) async {
     case 2:
       k += a;
       return k+2;
-    default: k = 2; /// withDefault: ok
+    default: k = 2; //# withDefault: ok
   }
   return k;
 }
@@ -59,7 +59,7 @@ foo4(value) async {
     case 2:
       k += 2;
       return 2 + k;
-    default: k = 2; /// withDefault: ok
+    default: k = 2; //# withDefault: ok
   }
   return k;
 }
@@ -69,20 +69,20 @@ futureOf(a) async => await a;
 test() async {
   Expect.equals(1, await foo1(1));
   Expect.equals(4, await foo1(2));
-  Expect.equals(2, await foo1(3)); /// withDefault: ok
-  Expect.equals(0, await foo1(3)); /// none: ok
+  Expect.equals(2, await foo1(3)); //# withDefault: ok
+  Expect.equals(0, await foo1(3)); //# none: ok
   Expect.equals(1, await foo2(futureOf(1)));
   Expect.equals(4, await foo2(futureOf(2)));
-  Expect.equals(2, await foo2(futureOf(3))); /// withDefault: ok
-  Expect.equals(0, await foo2(futureOf(3))); /// none: ok
+  Expect.equals(2, await foo2(futureOf(3))); //# withDefault: ok
+  Expect.equals(0, await foo2(futureOf(3))); //# none: ok
   Expect.equals(1, await foo3(1));
   Expect.equals(4, await foo3(2));
-  Expect.equals(2, await foo3(3)); /// withDefault: ok
-  Expect.equals(0, await foo3(3)); /// none: ok
+  Expect.equals(2, await foo3(3)); //# withDefault: ok
+  Expect.equals(0, await foo3(3)); //# none: ok
   Expect.equals(1, await foo4(futureOf(1)));
   Expect.equals(4, await foo4(futureOf(2)));
-  Expect.equals(2, await foo4(futureOf(3))); /// withDefault: ok
-  Expect.equals(0, await foo4(futureOf(3))); /// none: ok
+  Expect.equals(2, await foo4(futureOf(3))); //# withDefault: ok
+  Expect.equals(0, await foo4(futureOf(3))); //# none: ok
 }
 
 void main() {