Add bitmaps and skp output to Skia port

BUILD.gn

 # Copyright 2016 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.
 
 import("//build_overrides/v8.gni")
 import("//testing/test.gni")
 import("pdfium.gni")
 
 config("pdfium_config") {
   cflags = []
@@ skipping 563 matching lines @@
     "core/src/fxge/ge/fx_ge_text.cpp",
     "core/src/fxge/ge/fx_text_int.h",
   ]
 
   configs += [
     ":fxge_warnings",
     ":pdfium_config",
   ]
 
   if (pdf_use_skia) {
-    sources = [
+    sources += [
       "core/src/fxge/skia/fx_skia_device.cpp",
     ]
-    deps = [
+    deps += [
       "//skia",
     ]
   }
 
   if (is_win) {
     sources += [
       "core/src/fxge/win32/dwrite_int.h",
       "core/src/fxge/win32/fx_win32_device.cpp",
       "core/src/fxge/win32/fx_win32_dib.cpp",
       "core/src/fxge/win32/fx_win32_dwrite.cpp",
@@ skipping 899 matching lines @@
       "//v8:v8_libplatform",
     ]
     include_dirs += [
       "//v8",
       "//v8/include",
     ]
     configs += [ "//v8:external_startup_data" ]
   }
   configs += [ ":pdfium_config" ]
 }