[cleanup] Drop unused Allocate*String MacroAssembler instructions

src/x64/macro-assembler-x64.h

 // Copyright 2012 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_X64_MACRO_ASSEMBLER_X64_H_
 #define V8_X64_MACRO_ASSEMBLER_X64_H_
 
 #include "src/assembler.h"
 #include "src/bailout-reason.h"
 #include "src/base/flags.h"
@@ skipping 1303 matching lines @@
                     AllocationFlags flags);
 
   // Allocate a heap number in new space with undefined value. Returns
   // tagged pointer in result register, or jumps to gc_required if new
   // space is full.
   void AllocateHeapNumber(Register result,
                           Register scratch,
                           Label* gc_required,
                           MutableMode mode = IMMUTABLE);
 
-  // Allocate a sequential string. All the header fields of the string object
-  // are initialized.
-  void AllocateTwoByteString(Register result,
-                             Register length,
-                             Register scratch1,
-                             Register scratch2,
-                             Register scratch3,
-                             Label* gc_required);
-  void AllocateOneByteString(Register result, Register length,
-                             Register scratch1, Register scratch2,
-                             Register scratch3, Label* gc_required);
-
-  // Allocate a raw cons string object. Only the map field of the result is
-  // initialized.
-  void AllocateTwoByteConsString(Register result,
-                          Register scratch1,
-                          Register scratch2,
-                          Label* gc_required);
-  void AllocateOneByteConsString(Register result, Register scratch1,
-                                 Register scratch2, Label* gc_required);
-
-  // Allocate a raw sliced string object. Only the map field of the result is
-  // initialized.
-  void AllocateTwoByteSlicedString(Register result,
-                            Register scratch1,
-                            Register scratch2,
-                            Label* gc_required);
-  void AllocateOneByteSlicedString(Register result, Register scratch1,
-                                   Register scratch2, Label* gc_required);
-
   // Allocate and initialize a JSValue wrapper with the specified {constructor}
   // and {value}.
   void AllocateJSValue(Register result, Register constructor, Register value,
                        Register scratch, Label* gc_required);
 
   // ---------------------------------------------------------------------------
   // Support functions.
 
   // Check if result is zero and op is negative.
   void NegativeZeroTest(Register result, Register op, Label* then_label);
@@ skipping 348 matching lines @@
 inline Operand StackOperandForReturnAddress(int32_t disp) {
   return Operand(rsp, disp);
 }
 
 #define ACCESS_MASM(masm) masm->
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_