1. Dynamic compute the main closure that needs to be run by the main isolate

runtime/vm/precompiler.h

 // Copyright (c) 2015, 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.
 
 #ifndef RUNTIME_VM_PRECOMPILER_H_
 #define RUNTIME_VM_PRECOMPILER_H_
 
 #include "vm/allocation.h"
 #include "vm/hash_map.h"
 #include "vm/hash_table.h"
@@ skipping 413 matching lines @@
   Zone* zone() const { return zone_; }
   Isolate* isolate() const { return isolate_; }
 
   Thread* thread_;
   Zone* zone_;
   Isolate* isolate_;
 
   ParsedJSONObject* jit_feedback_;
 
   bool changed_;
+  bool retain_root_library_caches_;
   intptr_t function_count_;
   intptr_t class_count_;
   intptr_t selector_count_;
   intptr_t dropped_function_count_;
   intptr_t dropped_field_count_;
   intptr_t dropped_class_count_;
   intptr_t dropped_typearg_count_;
   intptr_t dropped_type_count_;
   intptr_t dropped_library_count_;
 
@@ skipping 41 matching lines @@
   }
   static RawObject* NewKey(const Function& function) { return function.raw(); }
 };
 
 typedef UnorderedHashSet<FunctionsTraits> UniqueFunctionsSet;
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_PRECOMPILER_H_