[turbofan] Fix merging of empty and non-empty state in load elimination.

src/compiler/load-elimination.cc

 // Copyright 2016 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/compiler/load-elimination.h"
 
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/simplified-operator.h"
 
@@ skipping 201 matching lines @@
   }
   return true;
 }
 
 void LoadElimination::AbstractState::Merge(AbstractState const* that,
                                            Zone* zone) {
   // Merge the information we have about the elements.
   if (this->elements_) {
     this->elements_ = that->elements_
                           ? that->elements_->Merge(this->elements_, zone)
-                          : that->elements_;
-  } else {
-    this->elements_ = that->elements_;
+                          : nullptr;
   }
 
   // Merge the information we have about the fields.
   for (size_t i = 0; i < arraysize(fields_); ++i) {
     if (this->fields_[i]) {
       if (that->fields_[i]) {
         this->fields_[i] = this->fields_[i]->Merge(that->fields_[i], zone);
       } else {
         this->fields_[i] = nullptr;
       }
@@ skipping 466 matching lines @@
   DCHECK_EQ(kTaggedBase, access.base_is_tagged);
   DCHECK_EQ(0, access.offset % kPointerSize);
   int field_index = access.offset / kPointerSize;
   if (field_index >= static_cast<int>(kMaxTrackedFields)) return -1;
   return field_index;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8