re-enable skia caching

core/fxge/ifx_renderdevicedriver.cpp

 // Copyright 2016 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "core/fxge/ifx_renderdevicedriver.h"
 
 #include "core/fxcrt/fx_coordinates.h"
 #include "core/fxge/cfx_pathdata.h"
@@ skipping 81 matching lines @@
 }
 
 bool IFX_RenderDeviceDriver::SetBitsWithMask(const CFX_DIBSource* pBitmap,
                                              const CFX_DIBSource* pMask,
                                              int left,
                                              int top,
                                              int bitmap_alpha,
                                              int blend_type) {
   return false;
 }
+
+#if defined _SKIA_SUPPORT_ || _SKIA_SUPPORT_PATHS_
+void IFX_RenderDeviceDriver::Flush() {}
+#endif