DevTools: use 'empty' for array holes

DevTools: use 'empty' for array holes

Console used to format holes in an Array very similarly to Array entries that
contained the value 'undefined'. The former showed up as 'undefined x n',
(e.g. `new Array(2)` or `[,,1]`) while the latter showed up as multiple
'undefined's (e.g. `[undefined, undefined]`). The two cases are functionally
different, since `0 in Array(1)` !== `0 in [undefined]`.

This CL reduces confusion by using 'empty x n' instead of 'undefined x n'
for holes in an Array.

BUG=732021
Review-Url: https://codereview.chromium.org/2977463002
Cr-Commit-Position: refs/heads/master@{#486173}
Committed: https://chromium.googlesource.com/chromium/src/+/072313e39845ddbd3174acddc64686b8fa12ca15

[luoe, 2017-07-08 01:16:37]

Description was changed from

==========
DevTools: use 'empty' for array holes

BUG=732021
==========

to

==========
DevTools: use 'empty' for array holes

Console used to format holes in an Array very similarly to Array entries that
contained the value 'undefined'. The former showed up as 'undefined x n',
(e.g. `new Array(2)` or `[,,1]`) while the latter showed up as multiple
'undefined's (e.g. `[undefined, undefined]`).

This CL reduces confusion by using 'empty x n' instead of 'undefined x n'
for holes in an Array. These are cases when testing for the property will return
false (e.g. `0 in Array(1)`).

BUG=732021
==========

[luoe, 2017-07-08 01:18:40]

Description was changed from

==========
DevTools: use 'empty' for array holes

Console used to format holes in an Array very similarly to Array entries that
contained the value 'undefined'. The former showed up as 'undefined x n',
(e.g. `new Array(2)` or `[,,1]`) while the latter showed up as multiple
'undefined's (e.g. `[undefined, undefined]`).

This CL reduces confusion by using 'empty x n' instead of 'undefined x n'
for holes in an Array. These are cases when testing for the property will return
false (e.g. `0 in Array(1)`).

BUG=732021
==========

to

==========
DevTools: use 'empty' for array holes

Console used to format holes in an Array very similarly to Array entries that
contained the value 'undefined'. The former showed up as 'undefined x n',
(e.g. `new Array(2)` or `[,,1]`) while the latter showed up as multiple
'undefined's (e.g. `[undefined, undefined]`). The two cases are functionally
different, since `0 in Array(1)` !== `0 in [undefined]`.

This CL reduces confusion by using 'empty x n' instead of 'undefined x n'
for holes in an Array.

BUG=732021
==========

[luoe, 2017-07-08 01:24:51]

luoe@chromium.org changed reviewers:
+ caseq@chromium.org, pfeldman@chromium.org

[luoe, 2017-07-08 01:24:53]

Alternatively, we could use `slots x n` or Firefox's `n empty slots`
(http://imgur.com/a/HNGsC)

caseq, pfeldman, what do you think?

[pfeldman, 2017-07-12 21:09:16]

lgtm

[luoe, 2017-07-12 21:09:50]

The CQ bit was checked by luoe@chromium.org

[commit-bot: I haz the power, 2017-07-12 21:10:21]

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, 2017-07-13 00:11:49]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1499893790658130, "parent_rev":
"38d333d060245ee5fda5c3a76254e3cf6bea1fe5", "commit_rev":
"277d3a431119129123d2ecefb1681791d43e9ef8"}

[commit-bot: I haz the power, 2017-07-13 00:12:07]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1499893790658130, "parent_rev":
"1fedb7496bda617c92432b17c6c5f89417d3d380", "commit_rev":
"8739a4d0fd78c633592d02440977328b18bb57af"}

[commit-bot: I haz the power, 2017-07-13 00:12:22]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1499893790658130, "parent_rev":
"106c0422016d35b03f80fbb40fe11146f75d3b20", "commit_rev":
"072313e39845ddbd3174acddc64686b8fa12ca15"}

[commit-bot: I haz the power, 2017-07-13 00:12:37]

Description was changed from

==========
DevTools: use 'empty' for array holes

Console used to format holes in an Array very similarly to Array entries that
contained the value 'undefined'. The former showed up as 'undefined x n',
(e.g. `new Array(2)` or `[,,1]`) while the latter showed up as multiple
'undefined's (e.g. `[undefined, undefined]`). The two cases are functionally
different, since `0 in Array(1)` !== `0 in [undefined]`.

This CL reduces confusion by using 'empty x n' instead of 'undefined x n'
for holes in an Array.

BUG=732021
==========

to

==========
DevTools: use 'empty' for array holes

Console used to format holes in an Array very similarly to Array entries that
contained the value 'undefined'. The former showed up as 'undefined x n',
(e.g. `new Array(2)` or `[,,1]`) while the latter showed up as multiple
'undefined's (e.g. `[undefined, undefined]`). The two cases are functionally
different, since `0 in Array(1)` !== `0 in [undefined]`.

This CL reduces confusion by using 'empty x n' instead of 'undefined x n'
for holes in an Array.

BUG=732021

Review-Url: https://codereview.chromium.org/2977463002
Cr-Commit-Position: refs/heads/master@{#486173}
Committed:
https://chromium.googlesource.com/chromium/src/+/072313e39845ddbd3174acddc646...
==========

[commit-bot: I haz the power, 2017-07-13 00:12:39]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/072313e39845ddbd3174acddc646...