Convert some GN test support targets to static libs.

ui/accessibility/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("//build/config/linux/pkg_config.gni")
 import("//build/config/ui.gni")
 import("//build/json_schema_api.gni")
 import("//testing/test.gni")
 if (is_android) {
   import("//build/config/android/rules.gni")
@@ skipping 105 matching lines @@
     srcjar_deps = [ ":ax_enumerations_srcjar" ]
   }
 
   java_cpp_enum("ax_enumerations_srcjar") {
     sources = [
       "ax_enums.idl",
     ]
   }
 }
 
-source_set("test_support") {
+static_library("test_support") {
   sources = [
     "platform/test_ax_node_wrapper.cc",
     "platform/test_ax_node_wrapper.h",
     "tree_generator.cc",
     "tree_generator.h",
   ]
 
   deps = [
     ":accessibility",
   ]
@@ skipping 29 matching lines @@
 json_schema_api("ax_gen") {
   sources = [
     "ax_enums.idl",
   ]
   deps = [
     "//base/third_party/dynamic_annotations",
   ]
   root_namespace = "ui"
   schemas = true
 }