[for-in] Sanitize for-in optimizations and fix bailout points.

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 5e17bbd58dfc9de67a4a44d9fc7da220a3865ef8..05753ffab945d05abecf554a71f48f9230ff04eb 100644
--- a/src/arm64/macro-assembler-arm64.cc
+++ b/src/arm64/macro-assembler-arm64.cc
@@ -1488,18 +1488,15 @@ void MacroAssembler::LoadAccessor(Register dst, Register holder,
 }
 
 
-void MacroAssembler::CheckEnumCache(Register object,
-                                    Register null_value,
-                                    Register scratch0,
-                                    Register scratch1,
-                                    Register scratch2,
-                                    Register scratch3,
+void MacroAssembler::CheckEnumCache(Register object, Register scratch0,
+                                    Register scratch1, Register scratch2,
+                                    Register scratch3, Register scratch4,
                                     Label* call_runtime) {
-  DCHECK(!AreAliased(object, null_value, scratch0, scratch1, scratch2,
-                     scratch3));
+  DCHECK(!AreAliased(object, scratch0, scratch1, scratch2, scratch3, scratch4));
 
   Register empty_fixed_array_value = scratch0;
   Register current_object = scratch1;
+  Register null_value = scratch4;
 
   LoadRoot(empty_fixed_array_value, Heap::kEmptyFixedArrayRootIndex);
   Label next, start;
@@ -1516,6 +1513,7 @@ void MacroAssembler::CheckEnumCache(Register object,
   Cmp(enum_length, kInvalidEnumCacheSentinel);
   B(eq, call_runtime);
 
+  LoadRoot(null_value, Heap::kNullValueRootIndex);
   B(&start);
 
   Bind(&next);