Add assert in the precompiler tree shaker to ensure that no redirecting

runtime/vm/precompiler.cc

 // 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.
 
 #include "vm/precompiler.h"
 
 #include "vm/aot_optimizer.h"
 #include "vm/assembler.h"
 #include "vm/ast_printer.h"
 #include "vm/branch_optimizer.h"
@@ skipping 984 matching lines @@
   AddType(type);
 
   if (cls.IsTypedefClass()) {
     AddTypesOf(Function::Handle(Z, cls.signature_function()));
   }
 }
 
 
 void Precompiler::AddTypesOf(const Function& function) {
   if (function.IsNull()) return;
+  // We don't expect to see a reference to a redicting factory.
+  ASSERT(!function.IsRedirectingFactory());
   if (functions_to_retain_.Lookup(&function) != NULL) return;
   functions_to_retain_.Insert(&Function::ZoneHandle(Z, function.raw()));
 
   AbstractType& type = AbstractType::Handle(Z);
   type = function.result_type();
   AddType(type);
   for (intptr_t i = 0; i < function.NumParameters(); i++) {
     type = function.ParameterTypeAt(i);
     AddType(type);
   }
@@ skipping 2640 matching lines @@
 
   ASSERT(FLAG_precompiled_mode);
   const bool optimized = function.IsOptimizable();  // False for natives.
   DartPrecompilationPipeline pipeline(zone, field_type_map);
   return PrecompileFunctionHelper(precompiler, &pipeline, function, optimized);
 }
 
 #endif  // DART_PRECOMPILER
 
 }  // namespace dart