[runtime] Use "the hole" instead of smi 0 as sentinel for context extension.

src/debug/debug-evaluate.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/debug/debug-evaluate.h"
 
 #include "src/accessors.h"
 #include "src/contexts.h"
 #include "src/debug/debug.h"
 #include "src/debug/debug-frames.h"
 #include "src/debug/debug-scopes.h"
 #include "src/frames-inl.h"
 #include "src/isolate-inl.h"
 
 namespace v8 {
 namespace internal {
 
 static inline bool IsDebugContext(Isolate* isolate, Context* context) {
   return context->native_context() == *isolate->debug()->debug_context();
 }
 
 
-MaybeHandle<Object> DebugEvaluate::Global(Isolate* isolate,
-                                          Handle<String> source,
-                                          bool disable_break,
-                                          Handle<Object> context_extension) {
+MaybeHandle<Object> DebugEvaluate::Global(
+    Isolate* isolate, Handle<String> source, bool disable_break,
+    Handle<HeapObject> context_extension) {
   // Handle the processing of break.
   DisableBreak disable_break_scope(isolate->debug(), disable_break);
 
   // Enter the top context from before the debugger was invoked.
   SaveContext save(isolate);
   SaveContext* top = &save;
   while (top != NULL && IsDebugContext(isolate, *top->context())) {
     top = top->prev();
   }
   if (top != NULL) isolate->set_context(*top->context());
 
   // Get the native context now set to the top context from before the
   // debugger was invoked.
   Handle<Context> context = isolate->native_context();
   Handle<JSObject> receiver(context->global_proxy());
   Handle<SharedFunctionInfo> outer_info(context->closure()->shared(), isolate);
   return Evaluate(isolate, outer_info, context, context_extension, receiver,
                   source);
 }
 
 
 MaybeHandle<Object> DebugEvaluate::Local(Isolate* isolate,
                                          StackFrame::Id frame_id,
                                          int inlined_jsframe_index,
                                          Handle<String> source,
                                          bool disable_break,
-                                         Handle<Object> context_extension) {
+                                         Handle<HeapObject> context_extension) {
   // Handle the processing of break.
   DisableBreak disable_break_scope(isolate->debug(), disable_break);
 
   // Get the frame where the debugging is performed.
   JavaScriptFrameIterator it(isolate, frame_id);
   JavaScriptFrame* frame = it.frame();
 
   // Traverse the saved contexts chain to find the active context for the
   // selected frame.
   SaveContext* save =
@@ skipping 10 matching lines @@
       isolate, context_builder.outer_info(),
       context_builder.innermost_context(), context_extension, receiver, source);
   if (!maybe_result.is_null()) context_builder.UpdateValues();
   return maybe_result;
 }
 
 
 // Compile and evaluate source for the given context.
 MaybeHandle<Object> DebugEvaluate::Evaluate(
     Isolate* isolate, Handle<SharedFunctionInfo> outer_info,
-    Handle<Context> context, Handle<Object> context_extension,
+    Handle<Context> context, Handle<HeapObject> context_extension,
     Handle<Object> receiver, Handle<String> source) {
   if (context_extension->IsJSObject()) {
     Handle<JSObject> extension = Handle<JSObject>::cast(context_extension);
     Handle<JSFunction> closure(context->closure(), isolate);
     context = isolate->factory()->NewWithContext(closure, context, extension);
   }
 
   Handle<JSFunction> eval_fun;
   ASSIGN_RETURN_ON_EXCEPTION(isolate, eval_fun,
                              Compiler::GetFunctionFromEval(
@@ skipping 209 matching lines @@
       // to materialize.
       return target;
   }
 
   return isolate_->factory()->NewCatchContext(
       function, target, isolate_->factory()->this_string(), receiver);
 }
 
 }  // namespace internal
 }  // namespace v8