Revert "[VM runtime] Store Smi instance type in type test cache when …

…using the interpreter."

This reverts commit 4cf2d39.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> [VM runtime] Store Smi instance type in type test cache when using the interpreter.
> 
> Instances of type Smi are handled in generated code and not looked up in
> type test cache. The interpreter does not implement this special handling and
> relies on the cache for Smi instances as well.
> 
> Change-Id: I3a8501efcbadfcbe848871ad0f6ada444414be43
> Reviewed-on: https://dart-review.googlesource.com/76305
> Reviewed-by: Zach Anderson <zra@google.com>
> Commit-Queue: Régis Crelier <regis@google.com>

TBR=vegorov@google.com,alexmarkov@google.com,zra@google.com,regis@google.com

Change-Id: I3cb0ced7520a62295e75ee92e4de2b5d41770676
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://dart-review.googlesource.com/76583
Reviewed-by: Régis Crelier <regis@google.com>
Commit-Queue: Régis Crelier <regis@google.com>

runtime/vm/runtime_entry.cc

@@ -637,24 +637,18 @@ static void UpdateTypeTestCache(
     }
     return;
   }
-  Class& instance_class = Class::Handle(zone);
   if (instance.IsSmi()) {
-    if (FLAG_enable_interpreter) {
-      instance_class = Smi::Class();
-    } else {
-      if (FLAG_trace_type_checks) {
-        OS::PrintErr("UpdateTypeTestCache: instance is Smi, not updating\n");
-      }
-      return;
+    if (FLAG_trace_type_checks) {
+      OS::PrintErr("UpdateTypeTestCache: instance is Smi\n");
     }
-  } else {
-    instance_class = instance.clazz();
+    return;
   }
   // If the type is uninstantiated and refers to parent function type
   // parameters, the function_type_arguments have been canonicalized
   // when concatenated.
   ASSERT(function_type_arguments.IsNull() ||
          function_type_arguments.IsCanonical());
+  const Class& instance_class = Class::Handle(zone, instance.clazz());
   auto& instance_class_id_or_function = Object::Handle(zone);
   auto& instance_type_arguments = TypeArguments::Handle(zone);
   auto& instance_parent_function_type_arguments = TypeArguments::Handle(zone);