Teach treeshaker about new cached functions and classes.

runtime/vm/precompiler.cc

Index: runtime/vm/precompiler.cc
diff --git a/runtime/vm/precompiler.cc b/runtime/vm/precompiler.cc
index 0f9d8d9883254f634d25fbb6c5e4a9231ee2ce41..422d60aaeea703f7a08b3520bb11b285c8f5b1ab 100644
--- a/runtime/vm/precompiler.cc
+++ b/runtime/vm/precompiler.cc
@@ -482,11 +482,19 @@ void Precompiler::DoCompileAll(
       DropScriptData();
       I->object_store()->set_unique_dynamic_targets(Array::null_array());
       Class& null_class = Class::Handle(Z);
+      Function& null_function = Function::Handle(Z);
       I->object_store()->set_future_class(null_class);
       I->object_store()->set_completer_class(null_class);
       I->object_store()->set_stream_iterator_class(null_class);
       I->object_store()->set_symbol_class(null_class);
       I->object_store()->set_compiletime_error_class(null_class);
+      I->object_store()->set_simple_instance_of_function(null_function);
+      I->object_store()->set_simple_instance_of_true_function(null_function);
+      I->object_store()->set_simple_instance_of_false_function(null_function);
+      I->object_store()->set_async_set_thread_stack_trace(null_function);
+      I->object_store()->set_async_star_move_next_helper(null_function);
+      I->object_store()->set_complete_on_async_return(null_function);
+      I->object_store()->set_async_star_stream_controller(null_class);
     }
     DropClasses();
     DropLibraries();