Fix Scanner invariants w/ literal buffers.

Fix Scanner invariants w/ literal buffers.

This isn't the most elegant fix, but I'd prefer to not rework the logic
right now. What happens is:
- Most parts of the Scanner use nullptr to mean, no literal buffer.
- The bookmarking logic may end up with a state where there's a non-nullptr
  literal buffer, but it's empty. (length 0)
- These are functionally equivalent, so there's no 'real' bug.
- But it makes it hard to reason. This patch hence checks for length-0
  literal buffers, and uses nullptr instead.

R=marja@chromium.org
BUG=chromium:639191
v8:4947

Committed: https://crrev.com/b68df2d27010b8fcf4f50f73644335dd584eecac
Cr-Commit-Position: refs/heads/master@{#38756}

[marja, 2016-08-19 12:12:07]

lgtm, seems trivial

[vogelheim, 2016-08-19 12:12:31]

Description was changed from

==========
Fix Scanner invariants w/ litteral buffers.

This isn't the most elegant fix, but I'd prefer to not rework the logic
right now. What happens is:
- Most parts of the Scanner use nullptr to mean, no literal buffer.
- The bookmarking logic may end up with a state where there's a non-nullptr
  literal buffer, but it's empty. (length 0)
- These are functionally equivalent, so there's no 'real' bug.
- But it makes it hard to reason. This patch hence checks for length-0
  literal buffers, and uses nullptr instead.

R=marja@chromium.org
BUG=chromium:639191 v8:4947
==========

to

==========
Fix Scanner invariants w/ literal buffers.

This isn't the most elegant fix, but I'd prefer to not rework the logic
right now. What happens is:
- Most parts of the Scanner use nullptr to mean, no literal buffer.
- The bookmarking logic may end up with a state where there's a non-nullptr
  literal buffer, but it's empty. (length 0)
- These are functionally equivalent, so there's no 'real' bug.
- But it makes it hard to reason. This patch hence checks for length-0
  literal buffers, and uses nullptr instead.

R=marja@chromium.org
BUG=chromium:639191 v8:4947
==========

[vogelheim, 2016-08-19 12:13:15]

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

[commit-bot: I haz the power, 2016-08-19 12:13:26]

Dry run: 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, 2016-08-19 13:21:08]

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

[commit-bot: I haz the power, 2016-08-19 13:21:09]

Dry run: This issue passed the CQ dry run.

[vogelheim, 2016-08-19 14:06:57]

The CQ bit was checked by vogelheim@chromium.org

[commit-bot: I haz the power, 2016-08-19 14:07:07]

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, 2016-08-19 15:25:13]

Description was changed from

==========
Fix Scanner invariants w/ literal buffers.

This isn't the most elegant fix, but I'd prefer to not rework the logic
right now. What happens is:
- Most parts of the Scanner use nullptr to mean, no literal buffer.
- The bookmarking logic may end up with a state where there's a non-nullptr
  literal buffer, but it's empty. (length 0)
- These are functionally equivalent, so there's no 'real' bug.
- But it makes it hard to reason. This patch hence checks for length-0
  literal buffers, and uses nullptr instead.

R=marja@chromium.org
BUG=chromium:639191 v8:4947
==========

to

==========
Fix Scanner invariants w/ literal buffers.

This isn't the most elegant fix, but I'd prefer to not rework the logic
right now. What happens is:
- Most parts of the Scanner use nullptr to mean, no literal buffer.
- The bookmarking logic may end up with a state where there's a non-nullptr
  literal buffer, but it's empty. (length 0)
- These are functionally equivalent, so there's no 'real' bug.
- But it makes it hard to reason. This patch hence checks for length-0
  literal buffers, and uses nullptr instead.

R=marja@chromium.org
BUG=chromium:639191 v8:4947
==========

[commit-bot: I haz the power, 2016-08-19 15:25:14]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-19 15:25:31]

Description was changed from

==========
Fix Scanner invariants w/ literal buffers.

This isn't the most elegant fix, but I'd prefer to not rework the logic
right now. What happens is:
- Most parts of the Scanner use nullptr to mean, no literal buffer.
- The bookmarking logic may end up with a state where there's a non-nullptr
  literal buffer, but it's empty. (length 0)
- These are functionally equivalent, so there's no 'real' bug.
- But it makes it hard to reason. This patch hence checks for length-0
  literal buffers, and uses nullptr instead.

R=marja@chromium.org
BUG=chromium:639191 v8:4947
==========

to

==========
Fix Scanner invariants w/ literal buffers.

This isn't the most elegant fix, but I'd prefer to not rework the logic
right now. What happens is:
- Most parts of the Scanner use nullptr to mean, no literal buffer.
- The bookmarking logic may end up with a state where there's a non-nullptr
  literal buffer, but it's empty. (length 0)
- These are functionally equivalent, so there's no 'real' bug.
- But it makes it hard to reason. This patch hence checks for length-0
  literal buffers, and uses nullptr instead.

R=marja@chromium.org
BUG=chromium:639191 v8:4947

Committed: https://crrev.com/b68df2d27010b8fcf4f50f73644335dd584eecac
Cr-Commit-Position: refs/heads/master@{#38756}
==========

[commit-bot: I haz the power, 2016-08-19 15:25:32]

Patchset 1 (id:??) landed as
https://crrev.com/b68df2d27010b8fcf4f50f73644335dd584eecac
Cr-Commit-Position: refs/heads/master@{#38756}