Remove high promotion mode.

src/arm64/macro-assembler-arm64.cc

Index: src/arm64/macro-assembler-arm64.cc
diff --git a/src/arm64/macro-assembler-arm64.cc b/src/arm64/macro-assembler-arm64.cc
index f485de4ee82c941327793c2435380952e9ad2143..75fd2b62be2641cfcc875f9c068c3d7d691b7758 100644
--- a/src/arm64/macro-assembler-arm64.cc
+++ b/src/arm64/macro-assembler-arm64.cc
@@ -3539,33 +3539,12 @@ void MacroAssembler::AllocateAsciiConsString(Register result,
                                              Register scratch1,
                                              Register scratch2,
                                              Label* gc_required) {
-  Label allocate_new_space, install_map;
-  AllocationFlags flags = TAG_OBJECT;
-
-  ExternalReference high_promotion_mode = ExternalReference::
-      new_space_high_promotion_mode_active_address(isolate());
-  Mov(scratch1, high_promotion_mode);
-  Ldr(scratch1, MemOperand(scratch1));
-  Cbz(scratch1, &allocate_new_space);
-
   Allocate(ConsString::kSize,
            result,
            scratch1,
            scratch2,
            gc_required,
-           static_cast<AllocationFlags>(flags | PRETENURE_OLD_POINTER_SPACE));
-
-  B(&install_map);
-
-  Bind(&allocate_new_space);
-  Allocate(ConsString::kSize,
-           result,
-           scratch1,
-           scratch2,
-           gc_required,
-           flags);
-
-  Bind(&install_map);
+           TAG_OBJECT);
 
   InitializeNewString(result,
                       length,