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 рф.

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

Review-Url: https://codereview.chromium.org/2683793010
Cr-Commit-Position: refs/heads/master@{#459226}
base::string16 StripWWWFromHost(const GURL& url) {
  DCHECK(url.is_valid());
  return StripWWW(base::ASCIIToUTF16(url.host_piece()));
}

base::string16 StripWWWFromHost(const GURL& url) {
  DCHECK(url.is_valid());
  return StripWWW(base::ASCIIToUTF16(url.host_piece()));
}
