Factor formal argument parsing into ParserBase

Factor formal argument parsing into ParserBase

This commit is a precursor to making lazy arrow function parsing use
similar logic to function(){} argument parsing.

Originally landed in these three CLs:

  https://codereview.chromium.org/1078093002
  https://codereview.chromium.org/1083623002
  https://codereview.chromium.org/1083953002

These were rolled out due to a performance regression on CodeLoad.  This
patchset will fix that by avoiding creation of a DuplicateFinder in the
full parser.

R=marja@chromium.org
BUG=
LOG=N

Committed: https://crrev.com/636cb4f365afe93de37685a69a9b8bfd16a9f70f
Cr-Commit-Position: refs/heads/master@{#27960}

[wingo, 2015-04-21 10:30:54]

Patchset #2 (id:20001) has been deleted

[wingo, 2015-04-21 10:32:34]

This is the purely refactoring bits of
https://codereview.chromium.org/1064433008/, split out into a new hopefully
easier-to-read changeset.  The first patchset contains the already reviewed
changes lists in the CL description.  The second refactors to add bindings
directly to the Scope and to avoid DuplicateFinder creation in the full parser.

[marja, 2015-04-21 10:40:27]

lgtm based on discussions & reviews in
https://codereview.chromium.org/1064433008/ and the previous version

[wingo, 2015-04-21 10:43:09]

The CQ bit was checked by wingo@igalia.com

[commit-bot: I haz the power, 2015-04-21 10:43:18]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1100713002/40001

[commit-bot: I haz the power, 2015-04-21 11:09:57]

Committed patchset #2 (id:40001)

[commit-bot: I haz the power, 2015-04-21 11:10:07]

Patchset 2 (id:??) landed as
https://crrev.com/636cb4f365afe93de37685a69a9b8bfd16a9f70f
Cr-Commit-Position: refs/heads/master@{#27960}

[marja, 2015-04-21 12:06:23]

At the moment, the performance bots look happy.. no visible regressions. To
confirm for realz we need a couple of more runs.