Use (Seeded)NumberDictionary instead.

Change-Id: I426cd0a33df7d47fe4fec0c108be5632ef7c0f19
Reviewed-on: https://chromium-review.googlesource.com/756697Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49179}