Revert "Type and constant propagator should guard against mutable class ids."

runtime/vm/constant_propagator.cc

Index: runtime/vm/constant_propagator.cc
diff --git a/runtime/vm/constant_propagator.cc b/runtime/vm/constant_propagator.cc
index 0736da7ec9338fde331e20f62c61c2d82d7d2cb0..67dc17b350b507004c16acfaad8e8b6a759c3446 100644
--- a/runtime/vm/constant_propagator.cc
+++ b/runtime/vm/constant_propagator.cc
@@ -788,14 +788,10 @@ void ConstantPropagator::VisitLoadClassId(LoadClassIdInstr* instr) {
     SetValue(instr, Smi::ZoneHandle(Z, Smi::New(cid)));
     return;
   }
-
   const Object& object = instr->object()->definition()->constant_value();
   if (IsConstant(object)) {
-    cid = object.GetClassId();
-    if (CheckClassInstr::IsImmutableClassId(cid)) {
-      SetValue(instr, Smi::ZoneHandle(Z, Smi::New(cid)));
-      return;
-    }
+    SetValue(instr, Smi::ZoneHandle(Z, Smi::New(object.GetClassId())));
+    return;
   }
   SetValue(instr, non_constant_);
 }