Allow access to context variables in optimized/inlined frames.

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 9529 matching lines @@
     NoGCScope no_gc;
     result ^= raw;
     result.set_num_variables(num_variables);
   }
   result.set_isolate(Isolate::Current());
   return result.raw();
 }
 
 
 const char* Context::ToCString() const {
+  if (IsNull()) {
+    return "Context (Null)";
+  }
   const Context& parent_ctx = Context::Handle(parent());
   if (parent_ctx.IsNull()) {
     const char* kFormat = "Context num_variables:% " Pd "";
     intptr_t len = OS::SNPrint(NULL, 0, kFormat, num_variables()) + 1;
     char* chars = Isolate::Current()->current_zone()->Alloc<char>(len);
     OS::SNPrint(chars, len, kFormat, num_variables());
     return chars;
   } else {
     const char* parent_str = parent_ctx.ToCString();
     const char* kFormat = "Context num_variables:% " Pd " parent:{ %s }";
@@ skipping 5942 matching lines @@
   return "_MirrorReference";
 }
 
 
 void MirrorReference::PrintToJSONStream(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
 }
 
 
 }  // namespace dart