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

src/compiler/js-typed-lowering.cc

 // Copyright 2014 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/code-factory.h"
 #include "src/compilation-dependencies.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/linkage.h"
@@ skipping 1819 matching lines @@
   DCHECK_EQ(IrOpcode::kJSCreateFunctionContext, node->opcode());
   int slot_count = OpParameter<int>(node->op());
   Node* const closure = NodeProperties::GetValueInput(node, 0);
 
   // Use inline allocation for function contexts up to a size limit.
   if (slot_count < kFunctionContextAllocationLimit) {
     // JSCreateFunctionContext[slot_count < limit]](fun)
     Node* effect = NodeProperties::GetEffectInput(node);
     Node* control = NodeProperties::GetControlInput(node);
     Node* context = NodeProperties::GetContextInput(node);
-    Node* extension = jsgraph()->ZeroConstant();
+    Node* extension = jsgraph()->TheHoleConstant();
     Node* native_context = effect = graph()->NewNode(
         javascript()->LoadContext(0, Context::NATIVE_CONTEXT_INDEX, true),
         context, context, effect);
     AllocationBuilder a(jsgraph(), effect, control);
     STATIC_ASSERT(Context::MIN_CONTEXT_SLOTS == 4);  // Ensure fully covered.
     int context_length = slot_count + Context::MIN_CONTEXT_SLOTS;
     a.AllocateArray(context_length, factory()->function_context_map());
     a.Store(AccessBuilder::ForContextSlot(Context::CLOSURE_INDEX), closure);
     a.Store(AccessBuilder::ForContextSlot(Context::PREVIOUS_INDEX), context);
     a.Store(AccessBuilder::ForContextSlot(Context::EXTENSION_INDEX), extension);
@@ skipping 738 matching lines @@
 }
 
 
 CompilationDependencies* JSTypedLowering::dependencies() const {
   return dependencies_;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8