Eliminate dependencies on assemblers and code stubs in precompiled runtime.

runtime/vm/ast_transformer.cc

Index: runtime/vm/ast_transformer.cc
diff --git a/runtime/vm/ast_transformer.cc b/runtime/vm/ast_transformer.cc
index 7ce398c8652eee9fe7a4f187342df9617b46c67a..b35494c855918e417415ce3b0fa0126dc562e27b 100644
--- a/runtime/vm/ast_transformer.cc
+++ b/runtime/vm/ast_transformer.cc
@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+#if !defined(DART_PRECOMPILED_RUNTIME)
+
 #include "vm/ast_transformer.h"
 
 #include "vm/object_store.h"
@@ -528,3 +530,5 @@ void AwaitTransformer::VisitThrowNode(ThrowNode* node) {
 }
 
 }  // namespace dart
+
+#endif  // !defined(DART_PRECOMPILED_RUNTIME)