Don't assume at least one closure function is encountered before tree-shaking. Allow…

runtime/vm/object.cc

 // 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.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 2323 matching lines @@
   Object& object = thread->ObjectHandle();
   dispatcher_cache ^= invocation_dispatcher_cache();
   object = dispatcher_cache.At(idx);
   if (!object.IsFunction()) {
     return Function::null();
   }
   return Function::Cast(object).raw();
 }
 
 
+void Class::set_closures(const GrowableObjectArray& value) const {
+  StorePointer(&raw_ptr()->closure_functions_, value.raw());
+}
+
+
 void Class::AddClosureFunction(const Function& function) const {
   GrowableObjectArray& closures =
       GrowableObjectArray::Handle(raw_ptr()->closure_functions_);
   if (closures.IsNull()) {
     closures = GrowableObjectArray::New(4, Heap::kOld);
     StorePointer(&raw_ptr()->closure_functions_, closures.raw());
   }
   ASSERT(function.IsNonImplicitClosureFunction());
   ASSERT(function.Owner() == this->raw());
   closures.Add(function, Heap::kOld);
@@ skipping 19213 matching lines @@
   return tag_label.ToCString();
 }
 
 
 void UserTag::PrintJSONImpl(JSONStream* stream, bool ref) const {
   Instance::PrintJSONImpl(stream, ref);
 }
 
 
 }  // namespace dart