Remove libxml dependency from Sky

sky/engine/core/BUILD.gn

 # Copyright 2014 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("//sky/engine/bindings/scripts/scripts.gni")
 import("//sky/engine/build/scripts/scripts.gni")
 import("//sky/engine/core/core.gni")
 
 visibility = ["//sky/engine/*"]
 
@@ skipping 97 matching lines @@
     "..:inside_blink",
   ]
 
   deps = [
     ":make_core_generated",
     ":prerequisites",
     "//gin",
     "//skia",
     "//third_party/iccjpeg",
     "//third_party/libpng",
-    "//third_party/libxml",
     "//third_party/qcms",
     "//sky/engine/bindings/core/v8:bindings_core_v8_generated",
     "//sky/engine/wtf",
     "//url",
     "//v8",
   ]
 
   include_dirs = [
     "$root_gen_dir/sky",
   ]
@@ skipping 341 matching lines @@
     "$sky_core_output_dir/{{source_name_part}}.h",
   ]
   args = [
     "{{source}}",
     rel_sky_core_gen_dir,
     bison_exe,
   ]
 
   deps = make_core_generated_deps
 }