This moves the implementation of @@replace from regexp.js to builtins-regexp.cc
(the TurboFan fast path) and runtime-regexp.cc (slow path). The fast path
handles all cases in which the regexp itself is an unmodified JSRegExp
instance, the given 'replace' argument is not callable and does not contain any
'$' characters (i.e. we are doing a string replacement).

BUG=v8:5339

Review-Url: https://codereview.chromium.org/2398423002
Cr-Commit-Position: refs/heads/master@{#40253}