[turbofan] Fix return value of Array.prototype.push.

src/compiler/js-builtin-reducer.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/compiler/js-builtin-reducer.h"
 
 #include "src/compilation-dependencies.h"
 #include "src/compiler/access-builder.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/node-matchers.h"
@@ skipping 295 matching lines @@
     elements = effect =
         graph()->NewNode(simplified()->MaybeGrowFastElements(flags), receiver,
                          elements, length, length, effect, control);
 
     // Append the value to the {elements}.
     effect = graph()->NewNode(
         simplified()->StoreElement(
             AccessBuilder::ForFixedArrayElement(receiver_map->elements_kind())),
         elements, length, value, effect, control);
 
+    // Return the new length of the {receiver}.
+    value = graph()->NewNode(simplified()->NumberAdd(), length,
+                             jsgraph()->OneConstant());
+
     ReplaceWithValue(node, value, effect, control);
     return Replace(value);
   }
   return NoChange();
 }
 
 namespace {
 
 bool HasInstanceTypeWitness(Node* receiver, Node* effect,
                             InstanceType instance_type) {
@@ skipping 1063 matching lines @@
   return jsgraph()->simplified();
 }
 
 JSOperatorBuilder* JSBuiltinReducer::javascript() const {
   return jsgraph()->javascript();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8