Fix disassembler crash with profiler

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 10185 matching lines @@
   const char* function_name = name.ToCString();
   jsobj.AddPropertyF("user_name", "%s%s", is_optimized() ? "*" : "",
                                           function_name);
   if (ref) {
     return;
   }
   jsobj.AddProperty("is_optimized", is_optimized());
   jsobj.AddProperty("is_alive", is_alive());
   jsobj.AddProperty("function", Object::Handle(function()));
   JSONArray jsarr(&jsobj, "disassembly");
-  DisassembleToJSONStream formatter(jsarr);
-  Disassemble(&formatter);
+  if (is_alive()) {
+    // Only disassemble alive code objects.
+    DisassembleToJSONStream formatter(jsarr);
+    Disassemble(&formatter);
+  }
 }
 
 
 uword Code::GetPatchCodePc() const {
   const PcDescriptors& descriptors = PcDescriptors::Handle(pc_descriptors());
   return descriptors.GetPcForKind(PcDescriptors::kPatchCode);
 }
 
 
 uword Code::GetLazyDeoptPc() const {
@@ skipping 7007 matching lines @@
   return "_MirrorReference";
 }
 
 
 void MirrorReference::PrintToJSONStream(JSONStream* stream, bool ref) const {
   Instance::PrintToJSONStream(stream, ref);
 }
 
 
 }  // namespace dart