Don't unescape BiDi control characters in URL components

      As per http://tools.ietf.org/html/rfc3987#section-4.1, the BiDi control
characters are not allowed in IRI.

Add constants for the new BiDi control characters from http://www.unicode.org/reports/tr9/ in rtl.h.

BUG=337746
TBR=rsleevi

Review URL: https://codereview.chromium.org/181483008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254091 0039d316-1c4b-4281-b951-d872f2087c98