Revert 20348 - "Fix LoadFieldByIndex to take mutable heap-numbers into account."

src/arm64/lithium-arm64.cc

Index: src/arm64/lithium-arm64.cc
diff --git a/src/arm64/lithium-arm64.cc b/src/arm64/lithium-arm64.cc
index 4bed135bca576a259a4e137bde030afdfd3d2c0c..6dccc5ffaa86218b80176f94843d5d8c3cd63fc9 100644
--- a/src/arm64/lithium-arm64.cc
+++ b/src/arm64/lithium-arm64.cc
@@ -2562,9 +2562,7 @@ LInstruction* LChunkBuilder::DoCheckMapValue(HCheckMapValue* instr) {
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegisterAtStart(instr->object());
   LOperand* index = UseRegister(instr->index());
-  LLoadFieldByIndex* load = new(zone()) LLoadFieldByIndex(object, index);
-  LInstruction* result = DefineSameAsFirst(load);
-  return AssignPointerMap(result);
+  return DefineAsRegister(new(zone()) LLoadFieldByIndex(object, index));
 }