[csa] Re-introduce automatic constant folding for IntPtrAdd and IntPtrSub

src/code-stub-assembler.h

 // 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.
 
 #ifndef V8_CODE_STUB_ASSEMBLER_H_
 #define V8_CODE_STUB_ASSEMBLER_H_
 
 #include <functional>
 
 #include "src/compiler/code-assembler.h"
@@ skipping 117 matching lines @@
 
 #define HEAP_CONSTANT_TEST(rootName, name) Node* Is##name(Node* value);
   HEAP_CONSTANT_LIST(HEAP_CONSTANT_TEST)
 #undef HEAP_CONSTANT_TEST
 
   Node* HashSeed();
   Node* StaleRegisterConstant();
 
   Node* IntPtrOrSmiConstant(int value, ParameterMode mode);
 
-  Node* IntPtrAddFoldConstants(Node* left, Node* right);
-  Node* IntPtrSubFoldConstants(Node* left, Node* right);
   // Round the 32bits payload of the provided word up to the next power of two.
   Node* IntPtrRoundUpToPowerOfTwo32(Node* value);
   // Select the maximum of the two provided IntPtr values.
   Node* IntPtrMax(Node* left, Node* right);
   // Select the minimum of the two provided IntPtr values.
   Node* IntPtrMin(Node* left, Node* right);
 
   // Float64 operations.
   Node* Float64Ceil(Node* x);
   Node* Float64Floor(Node* x);
@@ skipping 1066 matching lines @@
   }
 #else
 #define CSA_SLOW_ASSERT(csa, x) ((void)0)
 #endif
 
 DEFINE_OPERATORS_FOR_FLAGS(CodeStubAssembler::AllocationFlags);
 
 }  // namespace internal
 }  // namespace v8
 #endif  // V8_CODE_STUB_ASSEMBLER_H_