Fix warnings_checker.dart handling of multitests

tests/lib/mirrors/metadata_allowed_values_test.dart

Index: tests/lib/mirrors/metadata_allowed_values_test.dart
diff --git a/tests/lib/mirrors/metadata_allowed_values_test.dart b/tests/lib/mirrors/metadata_allowed_values_test.dart
index 92c43f576f9b0c0b6417c1ae738c1aa67a6811d1..b929f639444e004751103c3a874f3c405a346fee 100644
--- a/tests/lib/mirrors/metadata_allowed_values_test.dart
+++ b/tests/lib/mirrors/metadata_allowed_values_test.dart
@@ -10,7 +10,7 @@ import 'package:expect/expect.dart';
 import 'metadata_allowed_values_import.dart';  // Unprefixed.
 import 'metadata_allowed_values_import.dart' as prefix;
 
-@A // /// 01: compile-time error
+@A // //# 01: compile-time error
 class A {}
 
 @B.CONSTANT
@@ -30,43 +30,43 @@ class D {
   const D.named(this.field);
 }
 
-@E.NOT_CONSTANT // /// 02: compile-time error
+@E.NOT_CONSTANT // //# 02: compile-time error
 class E {
   static var NOT_CONSTANT = 3;
 }
 
-@F(6) // /// 03: compile-time error
+@F(6) // //# 03: compile-time error
 class F {
   final field;
   F(this.field);
 }
 
-@G.named(4) // /// 04: compile-time error
+@G.named(4) // //# 04: compile-time error
 class G {
   final field;
   G.named(this.field);
 }
 
-@H<int>() // /// 05: compile-time error
+@H<int>() // //# 05: compile-time error
 class H<T> {
   const H();
 }
 
-@I[0] // /// 06: compile-time error
+@I[0] // //# 06: compile-time error
 class I {}
 
-@this.toString // /// 07: compile-time error
+@this.toString // //# 07: compile-time error
 class J {}
 
-@super.toString // /// 08: compile-time error
+@super.toString // //# 08: compile-time error
 class K {}
 
-@L.func() // /// 09: compile-time error
+@L.func() // //# 09: compile-time error
 class L {
   static func() => 6;
 }
 
-@Imported // /// 10: compile-time error
+@Imported // //# 10: compile-time error
 class M {}
 
 @Imported()
@@ -78,7 +78,7 @@ class O {}
 @Imported.CONSTANT
 class P {}
 
-@prefix.Imported // /// 11: compile-time error
+@prefix.Imported // //# 11: compile-time error
 class Q {}
 
 @prefix.Imported()
@@ -90,84 +90,84 @@ class S {}
 @prefix.Imported.CONSTANT
 class T {}
 
-@U..toString() // /// 12: compile-time error
+@U..toString() // //# 12: compile-time error
 class U {}
 
-@V.tearOff // /// 13: compile-time error
+@V.tearOff // //# 13: compile-time error
 class V {
   static tearOff() {}
 }
 
 topLevelTearOff() => 4;
 
-@topLevelTearOff // /// 14: compile-time error
+@topLevelTearOff // //# 14: compile-time error
 class W {}
 
-@TypeParameter // /// 15: compile-time error
+@TypeParameter // //# 15: compile-time error
 class X<TypeParameter> {}
 
-@TypeParameter.member // /// 16: compile-time error
+@TypeParameter.member // //# 16: compile-time error
 class Y<TypeParameter> {}
 
-@1 // /// 17: compile-time error
+@1 // //# 17: compile-time error
 class Z {}
 
-@3.14 // /// 18: compile-time error
+@3.14 // //# 18: compile-time error
 class AA {}
 
-@'string' // /// 19: compile-time error
+@'string' // //# 19: compile-time error
 class BB {}
 
-@#symbol // /// 20: compile-time error
+@#symbol // //# 20: compile-time error
 class CC {}
 
-@['element'] // /// 21: compile-time error
+@['element'] // //# 21: compile-time error
 class DD {}
 
-@{'key': 'value'} // /// 22: compile-time error
+@{'key': 'value'} // //# 22: compile-time error
 class EE {}
 
-@true // /// 23: compile-time error
+@true // //# 23: compile-time error
 class FF {}
 
-@false // /// 24: compile-time error
+@false // //# 24: compile-time error
 class GG {}
 
-@null // /// 25: compile-time error
+@null // //# 25: compile-time error
 class HH {}
 
 const a = const [1, 2, 3];
 @a
 class II {}
 
-@a[0] // /// 26: compile-time error
+@a[0] // //# 26: compile-time error
 class JJ {}
 
-@kk // /// 27: compile-time error
+@kk // //# 27: compile-time error
 class KK {
   const KK();
 }
 get kk => const KK();
 
-@LL(() => 42) // /// 28: compile-time error
+@LL(() => 42) // //# 28: compile-time error
 class LL {
   final field;
   const LL(this.field);
 }
 
-@MM((x) => 42) // /// 29: compile-time error
+@MM((x) => 42) // //# 29: compile-time error
 class MM {
   final field;
   const MM(this.field);
 }
 
-@NN(() {}) // /// 30: compile-time error
+@NN(() {}) // //# 30: compile-time error
 class NN {
   final field;
   const NN(this.field);
 }
 
-@OO(() { () {} }) // /// 31: compile-time error
+@OO(() { () {} }) // //# 31: compile-time error
 class OO {
   final field;
   const OO(this.field);