RegExpParser: Fix Reset()ting to the end.

The bug would occur when we try to Reset() to a position already at the end.

This happens e.g., when the regexp ends with \u. What used to happen in that
case: 1) Advance past \ and u (to the end) (which wouldn't increase next_pos_
enough) 2) Try to parse 4 hex digits 3) When that failed, Reset() to the
position which should've been at the end but wasn't.

To be able to properly Reset() to a position at the end, we need to allow
next_pos_ to move beyond the end (since position() is next_pos_ - 1).

Minimal repro case:

var r = /foo\u/
r.test("foou") // should be true, was false.

(Note that \u not followed by 4 hex didits should be interpreted as an identity
escape. It already worked unless \u was at the end of the regexp.)

BUG=v8:3756
LOG=NO

Review URL: https://codereview.chromium.org/802313003

Cr-Commit-Position: refs/heads/master@{#25838}
Limit code size generated for very large regexps

R=jkummerow@chromium.org, yangguo@chromium.org
BUG=

Review URL: https://codereview.chromium.org/799403003

Cr-Commit-Position: refs/heads/master@{#25839}
[turbofan] Cache conversions inserted during typed lowering.

This greatly reduces the number of nodes in the graph (by more than 20x in
some extreme cases) for the Emscripten python interpreter main function.

BUG=v8:3763
LOG=y
TEST=cctest,mjsunit,unittests
R=svenpanne@chromium.org

Review URL: https://codereview.chromium.org/802353003

Cr-Commit-Position: refs/heads/master@{#25840}
[turbofan] enable stack slot reuse

BUG=

Review URL: https://codereview.chromium.org/793683002

Cr-Commit-Position: refs/heads/master@{#25841}
Introduced PropertyType ACCESSOR_FIELD.

Review URL: https://codereview.chromium.org/805453002

Cr-Commit-Position: refs/heads/master@{#25842}