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

src/arm/lithium-arm.cc

Index: src/arm/lithium-arm.cc
diff --git a/src/arm/lithium-arm.cc b/src/arm/lithium-arm.cc
index ba44b509e1cc9f3d2e81b4131957e8f5ec513c0b..c280999ca2b0849d7710fa89814d9ae472de7aa4 100644
--- a/src/arm/lithium-arm.cc
+++ b/src/arm/lithium-arm.cc
@@ -2539,9 +2539,7 @@ LInstruction* LChunkBuilder::DoCheckMapValue(HCheckMapValue* instr) {
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(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));
 }
 
 } }  // namespace v8::internal