Block domain labels made of Cyrillic letters that look alike Latin

      Block a label made entirely of Latin-look-alike Cyrillic letters when the TLD is not an IDN (i.e. this check is ON only for TLDs like 'com', 'net', 'uk', but not applied for IDN TLDs like ����.

BUG=683314
TEST=components_unittests --gtest_filter=U*IDN*

Review-Url: https://codereview.chromium.org/2683793010
Cr-Commit-Position: refs/heads/master@{#459226}