[cleanup] Drop unused Allocate*String MacroAssembler instructions

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 8b9bb60da67ec93c1488fd6e5f29b406551233d7..795ba912fad7c0b38ec8a3e436f45b06cb7928b9 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -1321,36 +1321,6 @@ class MacroAssembler: public Assembler {
                           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,