Allow including base/stl_util.h from Blink

Issue 837308 is going to replace arrraysize() with base::size(), but
base/stl_util.h (where base::size() is declared) is forbidden in
blink/renderer/DEPS,
while base/macros.h (where arraysize is declared) is allowed there.

This CL also allows including base/stl_util.h from blink/renderer.

Bug: 837308
Change-Id: Ifaf499dddbc99cec80c81c81f5588a2f6e3990a7
Reviewed-on: https://chromium-review.googlesource.com/1036597
Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#555168}

third_party/blink/renderer/DEPS

@@ -13,6 +13,7 @@ include_rules = [
     "+base/optional.h",
     "+base/sequenced_task_runner.h",
     "+base/single_thread_task_runner.h",
+    "+base/stl_util.h",
     "+base/task_scheduler/post_task.h",
     "+base/thread_annotations.h",
     "+base/threading/thread_checker.h",