Mapping several Indic characters to confusables.

A number of characters from several Indian scripts are confusable,
especially with numbers. This change maps these characters to their
ASCII lookalike to allow fallback to punycode when displaying probable
spoofing URLs.

Bug: 849421
Bug: 892646
Bug: 896722
Change-Id: I6d463642f3541454dc39bf4b32b8291417697c52
Reviewed-on: https://chromium-review.googlesource.com/c/1295179
Reviewed-by: Tommy Li <tommycli@chromium.org>
Commit-Queue: Joe DeBlasio <jdeblasio@chromium.org>
Cr-Commit-Position: refs/heads/master@{#602032}