[iOS] Support Dynamic Type for ReadingList empty string

This CL changes the string displayed when the ReadingList is empty so
it doesn't overflow below the bottom and top toolbar when the font is
too big. It does that by limiting the font size.

Bug: 893535
Cq-Include-Trybots: luci.chromium.try:ios-simulator-cronet;luci.chromium.try:ios-simulator-full-configs
Change-Id: I03335f2c1fee192a765b6e85011627c0f5ae2019
Reviewed-on: https://chromium-review.googlesource.com/c/1276925
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Reviewed-by: Kurt Horimoto <kkhorimoto@chromium.org>
Cr-Commit-Position: refs/heads/master@{#599153}
2 files changed