Correctly resolve local var shadowing a context-allocated var in debugger.

src/runtime.cc

 // Copyright 2012 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 12087 matching lines @@
   // Materialize the content of the local scope into a JSObject.
   Handle<JSObject> local_scope = MaterializeLocalScopeWithFrameInspector(
       isolate, frame, &frame_inspector);
   RETURN_IF_EMPTY_HANDLE(isolate, local_scope);
 
   // Allocate a new context for the debug evaluation and set the extension
   // object build.
   Handle<Context> context =
       isolate->factory()->NewFunctionContext(Context::MIN_CONTEXT_SLOTS,
                                              go_between);
-  context->set_extension(*local_scope);
+
+  // Use the materialized local scope in a with context.
+  context =
+      isolate->factory()->NewWithContext(go_between, context, local_scope);
+
   // Copy any with contexts present and chain them in front of this context.
   Handle<Context> frame_context(Context::cast(frame->context()));
   Handle<Context> function_context;
   // Get the function's context if it has one.
   if (scope_info->HasContext()) {
     function_context = Handle<Context>(frame_context->declaration_context());
   }
   context = CopyNestedScopeContextChain(isolate,
                                         go_between,
                                         context,
@@ skipping 1514 matching lines @@
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(Heap::kNoGCFlags,
                                        "Runtime::PerformGC");
   }
 }
 
 
 } }  // namespace v8::internal