Remove undefined-check from GetElementWithReceiver

src/objects.cc

 // Copyright 2013 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 <iomanip>
 #include <sstream>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 642 matching lines @@
   isolate->ReportFailedAccessCheck(object);
   RETURN_VALUE_IF_SCHEDULED_EXCEPTION(isolate, Nothing<PropertyAttributes>());
   return Just(ABSENT);
 }
 
 
 MaybeHandle<Object> Object::GetElementWithReceiver(Isolate* isolate,
                                                    Handle<Object> object,
                                                    Handle<Object> receiver,
                                                    uint32_t index) {
-  if (object->IsUndefined()) {
-    // TODO(verwaest): Why is this check here?
-    UNREACHABLE();
-    return isolate->factory()->undefined_value();
-  }
+  DCHECK(!object->IsUndefined());
 
   // Iterate up the prototype chain until an element is found or the null
   // prototype is encountered.
   for (PrototypeIterator iter(isolate, object,
                               object->IsJSProxy() || object->IsJSObject()
                                   ? PrototypeIterator::START_AT_RECEIVER
                                   : PrototypeIterator::START_AT_PROTOTYPE);
        !iter.IsAtEnd(); iter.Advance()) {
     if (PrototypeIterator::GetCurrent(iter)->IsJSProxy()) {
       return JSProxy::GetElementWithHandler(
@@ skipping 16569 matching lines @@
 void PropertyCell::SetValueWithInvalidation(Handle<PropertyCell> cell,
                                             Handle<Object> new_value) {
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 } }  // namespace v8::internal