Fix warnings_checker.dart handling of multitests

tests/language_strong/generic_methods_dynamic_test.dart

 // Copyright (c) 2017, 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.
 
 // Test that if the type of a parameter of a generic method is a type parameter,
 // the type of the passed argument is checked (01) at compile time
 // if the receiver is given via an interface-type variable, and (02) at runtime
 // if the receiver is dynamic.
 
 library generic_methods_dynamic_test;
 
 import "package:expect/expect.dart";
 
 class A {}
 
 class B {}
 
 class C {
   T foo<T>(T t) => t;
   List<T> bar<T>(Iterable<T> t) => <T>[t.first];
 }
 
 main() {
   B b = new B();
   C c = new C();
   dynamic obj = c;
 
-  c.foo<A>(b); /// 01: compile-time error
-  obj.foo<A>(b); /// 02: runtime error
+  c.foo<A>(b); //# 01: compile-time error
+  obj.foo<A>(b); //# 02: runtime error
 
-  c.bar<A>(<B>[new B()]); /// 03: compile-time error
-  obj.bar<A>(<B>[new B()]); /// 04: runtime error
+  c.bar<A>(<B>[new B()]); //# 03: compile-time error
+  obj.bar<A>(<B>[new B()]); //# 04: runtime error
 
-  Expect.equals(c.foo<B>(b), b); /// 05: ok
-  Expect.equals(obj.foo<B>(b), b); /// 05: continued
+  Expect.equals(c.foo<B>(b), b); //# 05: ok
+  Expect.equals(obj.foo<B>(b), b); //# 05: continued
 
-  dynamic x = c.bar<B>(<B>[new B()]); /// 05: continued
-  Expect.isTrue(x is List<B>); /// 05: continued
-  Expect.equals(x.length, 1); /// 05: continued
+  dynamic x = c.bar<B>(<B>[new B()]); //# 05: continued
+  Expect.isTrue(x is List<B>); //# 05: continued
+  Expect.equals(x.length, 1); //# 05: continued
 
-  dynamic y = obj.bar<B>(<B>[new B()]); /// 05: continued
-  Expect.isTrue(y is List<B>); /// 05: continued
-  Expect.equals(y.length, 1); /// 05: continued
+  dynamic y = obj.bar<B>(<B>[new B()]); //# 05: continued
+  Expect.isTrue(y is List<B>); //# 05: continued
+  Expect.equals(y.length, 1); //# 05: continued
 }