[Isolates] Fix auto extraction of isolate from heap objects in handle constructor.

src/debug.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 86 matching lines @@
       isolate,
       isolate->stub_cache()->ComputeCallDebugPrepareStepIn(argc, kind),
       Code);
 }
 
 
 static v8::Handle<v8::Context> GetDebugEventContext(Isolate* isolate) {
   Handle<Context> context = isolate->debug()->debugger_entry()->GetContext();
   // Isolate::context() may have been NULL when "script collected" event
   // occured.
-  if (*context == NULL) {
-    return v8::Local<v8::Context>();
-  }
+  if (context.is_null()) return v8::Local<v8::Context>();
   Handle<Context> global_context(context->global_context());
   return v8::Utils::ToLocal(global_context);
 }
 
 
 BreakLocationIterator::BreakLocationIterator(Handle<DebugInfo> debug_info,
                                              BreakLocatorType type) {
   debug_info_ = debug_info;
   type_ = type;
   reloc_iterator_ = NULL;
@@ skipping 724 matching lines @@
 
   // Create the debugger context.
   HandleScope scope;
   Handle<Context> context =
       isolate->bootstrapper()->CreateEnvironment(
           Handle<Object>::null(),
           v8::Handle<ObjectTemplate>(),
           NULL);
 
   // Use the debugger context.
-  SaveContext save;
+  SaveContext save(isolate);
   isolate->set_context(*context);
 
   // Expose the builtins object in the debugger context.
   Handle<String> key = FACTORY->LookupAsciiSymbol("builtins");
   Handle<GlobalObject> global = Handle<GlobalObject>(context->global());
   SetProperty(global, key, Handle<Object>(global->builtins()), NONE);
 
   // Compile the JavaScript for the debugger in the debugger context.
   isolate->debugger()->set_compiling_natives(true);
   bool caught_exception =
@@ skipping 2287 matching lines @@
     {
       Locker locker;
       Isolate::Current()->debugger()->CallMessageDispatchHandler();
     }
   }
 }
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal