Pass handles not raw objects into methods.

runtime/vm/debugger.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/debugger.h"
 
 #include "include/dart_api.h"
 
 #include "vm/code_generator.h"
 #include "vm/code_patcher.h"
@@ skipping 1368 matching lines @@
       }
     }
   } else if (resume_action_ == kStepInto) {
     // If the call target is not debuggable, we treat StepInto like
     // a StepOver, that is we instrument the current function.
     if (bpt->breakpoint_kind_ == PcDescriptors::kIcCall) {
       func_to_instrument = bpt->function();
       ICData& ic_data = ICData::Handle();
       Array& descriptor = Array::Handle();
       CodePatcher::GetInstanceCallAt(bpt->pc_, &ic_data, &descriptor);
-      ArgumentsDescriptor arg_descriptor(descriptor.raw());
+      ArgumentsDescriptor arg_descriptor(descriptor);
       ActivationFrame* top_frame = stack_trace->ActivationFrameAt(0);
       intptr_t num_args = arg_descriptor.Count();
       Instance& receiver =
           Instance::Handle(top_frame->GetInstanceCallReceiver(num_args));
       Code& code =
           Code::Handle(ResolveCompileInstanceCallTarget(receiver,
                                                         ic_data,
                                                         arg_descriptor));
       if (!code.IsNull()) {
         Function& callee = Function::Handle(code.function());
@@ skipping 217 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart