Really remove config.h

sky/engine/tonic/dart_gc_context.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "sky/engine/config.h"
 #include "sky/engine/tonic/dart_gc_context.h"
 
 namespace blink {
 
 DartGCContext::DartGCContext() : builder_(Dart_NewWeakReferenceSetBuilder()) {
 }
 
 DartGCContext::~DartGCContext() {
 }
 
 Dart_WeakReferenceSet DartGCContext::AddToSetForRoot(
     const void* root,
     Dart_WeakPersistentHandle handle) {
   const auto& it = references_.add(root, nullptr);
   if (!it.isNewEntry) {
     Dart_AppendToWeakReferenceSet(it.storedValue->value, handle, handle);
     return it.storedValue->value;
   }
   it.storedValue->value = Dart_NewWeakReferenceSet(builder_, handle, handle);
   return it.storedValue->value;
 }
 
 }  // namespace blink