Turn LoadIndexedInterceptor into a Turbofan stub

src/compiler/code-stub-assembler.h

 // 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.
 
 #ifndef V8_COMPILER_CODE_STUB_ASSEMBLER_H_
 #define V8_COMPILER_CODE_STUB_ASSEMBLER_H_
 
 #include <map>
 
 // Clients of this interface shouldn't depend on lots of compiler internals.
@@ skipping 255 matching lines @@
   Node* SmiLessThan(Node* a, Node* b);
   Node* SmiLessThanOrEqual(Node* a, Node* b);
   Node* SmiMin(Node* a, Node* b);
 
   // Load a value from the root array.
   Node* LoadRoot(Heap::RootListIndex root_index);
 
   // Check a value for smi-ness
   Node* WordIsSmi(Node* a);
 
+  // Check that the value is a positive smi.
+  Node* WordIsPositiveSmi(Node* a);
+
   // Load an object pointer from a buffer that isn't in the heap.
   Node* LoadBufferObject(Node* buffer, int offset,
                          MachineType rep = MachineType::AnyTagged());
   // Load a field from an object on the heap.
   Node* LoadObjectField(Node* object, int offset,
                         MachineType rep = MachineType::AnyTagged());
   // Load the floating point value of a HeapNumber.
   Node* LoadHeapNumberValue(Node* object);
   // Load the bit field of a Map.
   Node* LoadMapBitField(Node* map);
@@ skipping 124 matching lines @@
   // Map of variables to the list of value nodes that have been added from each
   // merge path in their order of merging.
   std::map<Variable::Impl*, std::vector<Node*>> variable_merges_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_CODE_STUB_ASSEMBLER_H_