Introduce a lazy-compile stub for functions.

runtime/vm/gc_marker.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 #include "vm/gc_marker.h"
 
 #include <map>
 #include <utility>
 #include <vector>
 
@@ skipping 231 matching lines @@
   }
 
   void DetachCode() {
     for (int i = 0; i < skipped_code_functions_.length(); i++) {
       RawFunction* func = skipped_code_functions_[i];
       RawCode* code = func->ptr()->code_;
       if (!code->IsMarked()) {
         // If the code wasn't strongly visited through other references
         // after skipping the function's code pointer, then we disconnect the
         // code from the function.
-        func->ptr()->code_ = Code::null();
+        func->ptr()->code_ = StubCode::LazyCompile_entry()->code();
         func->ptr()->unoptimized_code_ = Code::null();
         if (FLAG_log_code_drop) {
           // NOTE: This code runs while GC is in progress and runs within
           // a NoHandleScope block. Hence it is not okay to use a regular Zone
           // or Scope handle. We use a direct stack handle so the raw pointer in
           // this handle is not traversed. The use of a handle is mainly to
           // be able to reuse the handle based code and avoid having to add
           // helper functions to the raw object interface.
           String name;
           name = func->ptr()->name_;
@@ skipping 234 matching lines @@
   MarkingWeakVisitor mark_weak;
   IterateWeakRoots(isolate, &mark_weak, invoke_api_callbacks);
   mark.Finalize();
   ProcessWeakTables(page_space);
   ProcessObjectIdTable(isolate);
 
   Epilogue(isolate, invoke_api_callbacks);
 }
 
 }  // namespace dart