[SH iOS] Cleanup kScrollToTextIOS flag

This flag is on-by-default and launched to 100%, and has been for a long
time. This CL removes all references and dead code.

Bug: 1099268
Change-Id: I947b25f6d177c6d9422c1acf7235b120c9f80e0c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2837425
Commit-Queue: Tommy Martino <tmartino@chromium.org>
Reviewed-by: Ali Juma <ajuma@chromium.org>
Reviewed-by: Sebastien Lalancette <seblalancette@chromium.org>
Cr-Commit-Position: refs/heads/master@{#874835}
GitOrigin-RevId: 9dd82931047186a08e66f774bcf52112594f67bb
9 files changed