Don’t replace \x08 with \b in regular expressions

[mathiasbynens]

In regular expressions, \b has a different meaning than in strings (where it’s equivalent to '\x08'`):

/\b/.test('\b'); // false
/\x08/.test('\b'); // true

But jsesc incorrectly replaces \x08 in regular expressions with \b:

jsesc(/\x08/); // '/\\b/'

Only these single character escapes have the same meaning in regular expressions as in strings:

\f \n \r \t \v \0

Also see #11: \B, \w, \W, \s, \S, \d, \D, \cM, etc. should be preserved.

[mathiasbynens]

Relevant: mishoo/UglifyJS#54 (comment)