Move hash code from hidden string to a private symbol

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 721720fb8be1266e8e00a8a7b341b4cf9b08213e..e15edc94be7095123ae85cf4f2ccbc4f55cecb93 100644
--- a/src/arm64/macro-assembler-arm64.cc
+++ b/src/arm64/macro-assembler-arm64.cc
@@ -3928,6 +3928,7 @@ void MacroAssembler::GetNumberHash(Register key, Register scratch) {
   Add(key, key, scratch);
   // hash = hash ^ (hash >> 16);
   Eor(key, key, Operand(key, LSR, 16));
+  Bic(key, key, Operand(0xc0000000u));
 }