Fix stuff

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 "vm/code_generator.h"
 #include "vm/code_patcher.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1266 matching lines @@
     }
   } else {
     ASSERT(resume_action_ == kStepOut);
     // Set stepping breakpoints in the caller.
     if (stack_trace->Length() > 1) {
       ActivationFrame* caller_frame = stack_trace->ActivationFrameAt(1);
       func_to_instrument = caller_frame->DartFunction().raw();
     }
   }
 
-  if (func_to_instrument.raw() != currently_instrumented_func.raw()) {
+  if (func_to_instrument.IsNull() ||
+      (func_to_instrument.raw() != currently_instrumented_func.raw())) {
     last_bpt_line_ = -1;
     RemoveInternalBreakpoints();  // *bpt is now invalid.
     if (!func_to_instrument.IsNull()) {
       InstrumentForStepping(func_to_instrument);
     }
   }
 }
 
 
 void Debugger::Initialize(Isolate* isolate) {
@@ skipping 166 matching lines @@
 }
 
 
 void Debugger::RegisterCodeBreakpoint(CodeBreakpoint* bpt) {
   ASSERT(bpt->next() == NULL);
   bpt->set_next(code_breakpoints_);
   code_breakpoints_ = bpt;
 }
 
 }  // namespace dart