DBC: Use type cache for more checks

runtime/vm/flow_graph_compiler_dbc.cc

Index: runtime/vm/flow_graph_compiler_dbc.cc
diff --git a/runtime/vm/flow_graph_compiler_dbc.cc b/runtime/vm/flow_graph_compiler_dbc.cc
index 749d20a82c1104d20c11ea7bec02749f87bd0900..75bf2c54fa7547c9cb98eec14701d9117715e1ed 100644
--- a/runtime/vm/flow_graph_compiler_dbc.cc
+++ b/runtime/vm/flow_graph_compiler_dbc.cc
@@ -222,6 +222,9 @@ void FlowGraphCompiler::GenerateAssertAssignable(TokenPosition token_pos,
   SubtypeTestCache& test_cache = SubtypeTestCache::Handle();
   if (!dst_type.IsVoidType() && dst_type.IsInstantiated()) {
     test_cache = SubtypeTestCache::New();
+  } else if (!dst_type.IsInstantiated() &&
+             (dst_type.IsTypeParameter() || dst_type.IsType())) {
+    test_cache = SubtypeTestCache::New();
   }
 
   if (is_optimizing()) {