Tree shaker:

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 384 matching lines @@
   void TraceConstFunctions();
   void CollectCallbackFields();
 
   void TraceForRetainedFunctions();
   void DropFunctions();
   void DropFields();
   void TraceTypesFromRetainedClasses();
   void DropTypes();
   void DropTypeArguments();
   void DropScriptData();
+  void DropLibraryEntries();
   void DropClasses();
   void DropLibraries();
 
   void BindStaticCalls();
   void SwitchICCalls();
   void ResetPrecompilerState();
 
   void CollectDynamicFunctionNames();
 
   void PrecompileStaticInitializers();
@@ skipping 69 matching lines @@
   }
   static RawObject* NewKey(const Function& function) { return function.raw(); }
 };
 
 typedef UnorderedHashSet<FunctionsTraits> UniqueFunctionsSet;
 
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_PRECOMPILER_H_