[compiler] Fix typing of ToLength.

[compiler] Fix typing of ToLength.

Typer::Visitor::ToLength was unsound (and non-monotonic).  For instance,
if the input type was Range(2^53, 2^53+1), the result type was
Constant(2^53).  Now the result is type Constant(2^53-1).  (The result
of ToLength is guaranteed to be between 0 and 2^53-1.)

BUG=

Review-Url: https://codereview.chromium.org/2753773010
Cr-Commit-Position: refs/heads/master@{#43914}
Committed: https://chromium.googlesource.com/v8/v8/+/1b696f3cec27d3d304e8036d036c4b99899faf04

[neis, 2017-03-17 15:51:24]

The CQ bit was checked by neis@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-03-17 15:51:36]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[neis, 2017-03-17 15:52:50]

neis@chromium.org changed reviewers:
+ jarin@chromium.org

[neis, 2017-03-17 15:52:50]

PTAL.

Tests for monotonicity are in the followup CL. Tests for soundness don't exist
yet.

[Jarin, 2017-03-17 16:13:29]

lgtm, great catch!

[commit-bot: I haz the power, 2017-03-17 16:40:10]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-03-17 16:40:11]

Dry run: This issue passed the CQ dry run.

[neis, 2017-03-17 18:43:34]

The CQ bit was checked by neis@chromium.org

[commit-bot: I haz the power, 2017-03-17 18:43:40]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-17 18:45:17]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1489776214557540, "parent_rev":
"771e86fdf2cf46f11019210ee37f88711a76a8f2", "commit_rev":
"1b696f3cec27d3d304e8036d036c4b99899faf04"}

[commit-bot: I haz the power, 2017-03-17 18:45:22]

Description was changed from

==========
[compiler] Fix typing of ToLength.

Typer::Visitor::ToLength was unsound (and non-monotonic).  For instance,
if the input type was Range(2^53, 2^53+1), the result type was
Constant(2^53).  Now the result is type Constant(2^53-1).  (The result
of ToLength is guaranteed to be between 0 and 2^53-1.)

BUG=
==========

to

==========
[compiler] Fix typing of ToLength.

Typer::Visitor::ToLength was unsound (and non-monotonic).  For instance,
if the input type was Range(2^53, 2^53+1), the result type was
Constant(2^53).  Now the result is type Constant(2^53-1).  (The result
of ToLength is guaranteed to be between 0 and 2^53-1.)

BUG=

Review-Url: https://codereview.chromium.org/2753773010
Cr-Commit-Position: refs/heads/master@{#43914}
Committed:
https://chromium.googlesource.com/v8/v8/+/1b696f3cec27d3d304e8036d036c4b99899...
==========

[commit-bot: I haz the power, 2017-03-17 18:45:23]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/v8/v8/+/1b696f3cec27d3d304e8036d036c4b99899...