Introduce a lazy-compile stub for functions.

runtime/vm/compiler.cc

 // Copyright (c) 2012, 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/compiler.h"
 
 #include "vm/assembler.h"
 
 #include "vm/ast_printer.h"
 #include "vm/block_scheduler.h"
@@ skipping 548 matching lines @@
         graph_compiler.FinalizeStaticCallTargetsTable(code);
 
         if (optimized) {
           if (osr_id == Isolate::kNoDeoptId) {
             CodePatcher::PatchEntry(Code::Handle(function.CurrentCode()));
             if (FLAG_trace_compiler) {
               OS::Print("--> patching entry %#" Px "\n",
                   Code::Handle(function.unoptimized_code()).EntryPoint());
             }
           }
-          function.SetCode(code);
+          function.AttachCode(code);
 
           for (intptr_t i = 0;
                i < flow_graph->guarded_fields()->length();
                i++) {
             const Field* field = (*flow_graph->guarded_fields())[i];
             field->RegisterDependentCode(code);
           }
         } else {
           function.set_unoptimized_code(code);
-          function.SetCode(code);
+          function.AttachCode(code);
           ASSERT(CodePatcher::CodeIsPatchable(code));
         }
         if (parsed_function->HasDeferredPrefixes()) {
           GrowableObjectArray* prefixes = parsed_function->DeferredPrefixes();
           LibraryPrefix& prefix = LibraryPrefix::Handle();
           for (intptr_t i = 0; i < prefixes->Length(); i++) {
             prefix ^= prefixes->At(i);
             prefix.RegisterDependentCode(code);
           }
         }
@@ skipping 369 matching lines @@
     const Object& result =
       Object::Handle(isolate->object_store()->sticky_error());
     isolate->object_store()->clear_sticky_error();
     return result.raw();
   }
   UNREACHABLE();
   return Object::null();
 }
 
 }  // namespace dart