Code review comment for lp://qastaging/~angeloc/unity-lens-files/fix-for-948086

Can we move all the TLDs into a const string, so that we'll have just:

web_regex = new Regex ("(http[s]{0,1}://.+){0,1}[a-zA-Z0-9\\-\\.]+\\." + TLD_REGEX + "$");

Also, this regex should be definitely compiled with RegexCompileFlags.OPTIMIZE