This ports RegExpInitialize, IsRegExp, InternalMatch and InternalReplace to C++
/ TurboFan. InternalMatch is in TurboFan because it calls RegExpExecStub and
needs to construct a RegExpResult (which are, respectively, a PlatformStub and
a CodeStubAssembler function).

Except for LastMatchInfo (and GetSubstitution, which could be moved to string.js
anytime), regexp.js is now completely empty.

BUG=v8:5339

Review-Url: https://codereview.chromium.org/2409513003
Cr-Commit-Position: refs/heads/master@{#40277}