GN: Add make_core_generated->m..private_script dep

This is needed to build the generated bindings.

R=brettw@chromium.org

Review URL: https://codereview.chromium.org/359693002

git-svn-id: svn://svn.chromium.org/blink/trunk@177159 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/BUILD.gn

@@ -565,6 +565,7 @@ action("generated_testing_idls_internal_runtime_flags") {
 # GYP version: WebKit/Source/core/core_generated.gyp:make_core_generated
 group("make_core_generated") {
   deps = [
+    ":make_core_generated_private_script",
     ":make_core_generated_xml_viewer_css",
     ":make_core_generated_xml_viewer_js",
     ":make_core_generated_html_entity_table",