VM: Avoid smi-check when loading class-ids from known non-smi values

runtime/vm/flow_graph_type_propagator.cc

Index: runtime/vm/flow_graph_type_propagator.cc
diff --git a/runtime/vm/flow_graph_type_propagator.cc b/runtime/vm/flow_graph_type_propagator.cc
index b1d188aef4ef11ead3b9c9e24ebb12c2dbbde78f..8accbf47b9e6747515dbd95ed29262a385c5e115 100644
--- a/runtime/vm/flow_graph_type_propagator.cc
+++ b/runtime/vm/flow_graph_type_propagator.cc
@@ -466,6 +466,11 @@ CompileType CompileType::Int() {
 }
 
 
+CompileType CompileType::Smi() {
+  return Create(kSmiCid, Type::ZoneHandle(Type::SmiType()));
+}
+
+
 CompileType CompileType::String() {
   return FromAbstractType(Type::ZoneHandle(Type::StringType()), kNonNullable);
 }