Add some src/webkit build files to the GN build.

webkit/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("//tools/grit/grit_rule.gni")
+
+group("resources") {
+  deps = [
+    ":webkit_resources_action",
+    ":blink_common_resources",
+  ]
+}
+
+grit("webkit_resources_action") {
+  visibility = ":resources"
+  source = "glue/resources/webkit_resources.grd"
+}
+
+grit("blink_common_resources") {
+  visibility = ":resources"
+  source = "//third_party/WebKit/public/blink_resources.grd"
+}
+
+# webkit_strings in webkit_resources.gyp
+grit("strings") {
+  source = "glue/webkit_strings.grd"
+}