Ensure the url provided to a library has a computed hash code

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 0c0415f55bd956e4b7e42d7c4f240e89ef42ce50..0f8bc131d9ecfce26d09e4c819b9750f6959adcf 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -10364,6 +10364,8 @@ RawLibrary* Library::NewLibraryHelper(const String& url,
   Thread* thread = Thread::Current();
   Zone* zone = thread->zone();
   ASSERT(thread->IsMutatorThread());
+  // Force the url to have a hash code.
+  url.Hash();
   const Library& result = Library::Handle(zone, Library::New());
   result.StorePointer(&result.raw_ptr()->name_, Symbols::Empty().raw());
   result.StorePointer(&result.raw_ptr()->url_, url.raw());