Make EphemeralRange constructor not to accept invalid start and end positions

Make EphemeralRange to accept only valid positions

This patch introduces |DCHECK_LE(start, end)| for start and end positions of
|EphemeralRange| constructor and changing call sites of constructor for
wrong start/end parameter case, to catch wrong call sites for improving code
health and ease of debugging.

This patch is intended to help to find the root cause of crbug.com/624335, which
causes null pointer reference for iterating over |nodeAsRangeFirstNode()|
of start of range to |nodeAsRangePastLastNode()| of end of range. We would
like to know which call site makes this wrong range.

BUG=624335
TEST=Covered by existing test

Committed: https://crrev.com/4fb42e48b7175ccfabd887dc3ebb80a1697139e7
Cr-Commit-Position: refs/heads/master@{#404308}

[yosin_UTC9, 2016-07-07 07:13:08]

Description was changed from

==========
2016-07-07T15:58:08

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

to

==========
2016-07-07T15:58:08

BUG=624335
==========

[yosin_UTC9, 2016-07-08 01:30:08]

Description was changed from

==========
2016-07-07T15:58:08

BUG=624335
==========

to

==========
Make EphemeralRange to accept only valid positions

This patch introduces |DCHECK_LE(start, end)| for start and end positions of
|EphemeralRange| constructor and changing call sites of constructor for
wrong start/end parameter case, to catch wrong call sites for improving code
health and ease of debugging.

This patch should help to find the root cause of crbug.com/624335, which
causes null pointer reference for iterating over |nodeAsRangeFirstNode()|
of start of range to |nodeAsRangePastLastNode()| of end of range. We would
like to know which call site makes this wrong range.

BUG=624335
TEST=Covered by existing test
==========

[yosin_UTC9, 2016-07-08 01:31:21]

yosin@chromium.org changed reviewers:
+ xiaochengh@chromium.org, yoichio@chromium.org

[yosin_UTC9, 2016-07-08 01:31:21]

PTAL

[yosin_UTC9, 2016-07-08 01:31:59]

Description was changed from

==========
Make EphemeralRange to accept only valid positions

This patch introduces |DCHECK_LE(start, end)| for start and end positions of
|EphemeralRange| constructor and changing call sites of constructor for
wrong start/end parameter case, to catch wrong call sites for improving code
health and ease of debugging.

This patch should help to find the root cause of crbug.com/624335, which
causes null pointer reference for iterating over |nodeAsRangeFirstNode()|
of start of range to |nodeAsRangePastLastNode()| of end of range. We would
like to know which call site makes this wrong range.

BUG=624335
TEST=Covered by existing test
==========

to

==========
Make EphemeralRange to accept only valid positions

This patch introduces |DCHECK_LE(start, end)| for start and end positions of
|EphemeralRange| constructor and changing call sites of constructor for
wrong start/end parameter case, to catch wrong call sites for improving code
health and ease of debugging.

This patch is intended to help to find the root cause of crbug.com/624335, which
causes null pointer reference for iterating over |nodeAsRangeFirstNode()|
of start of range to |nodeAsRangePastLastNode()| of end of range. We would
like to know which call site makes this wrong range.

BUG=624335
TEST=Covered by existing test
==========

[yoichio, 2016-07-08 01:50:11]

lgtm

[yosin_UTC9, 2016-07-08 02:04:17]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2016-07-08 02:04:52]

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, 2016-07-08 02:09:51]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-07-08 02:11:44]

Description was changed from

==========
Make EphemeralRange to accept only valid positions

This patch introduces |DCHECK_LE(start, end)| for start and end positions of
|EphemeralRange| constructor and changing call sites of constructor for
wrong start/end parameter case, to catch wrong call sites for improving code
health and ease of debugging.

This patch is intended to help to find the root cause of crbug.com/624335, which
causes null pointer reference for iterating over |nodeAsRangeFirstNode()|
of start of range to |nodeAsRangePastLastNode()| of end of range. We would
like to know which call site makes this wrong range.

BUG=624335
TEST=Covered by existing test
==========

to

==========
Make EphemeralRange to accept only valid positions

This patch introduces |DCHECK_LE(start, end)| for start and end positions of
|EphemeralRange| constructor and changing call sites of constructor for
wrong start/end parameter case, to catch wrong call sites for improving code
health and ease of debugging.

This patch is intended to help to find the root cause of crbug.com/624335, which
causes null pointer reference for iterating over |nodeAsRangeFirstNode()|
of start of range to |nodeAsRangePastLastNode()| of end of range. We would
like to know which call site makes this wrong range.

BUG=624335
TEST=Covered by existing test

Committed: https://crrev.com/4fb42e48b7175ccfabd887dc3ebb80a1697139e7
Cr-Commit-Position: refs/heads/master@{#404308}
==========

[commit-bot: I haz the power, 2016-07-08 02:11:45]

Patchset 2 (id:??) landed as
https://crrev.com/4fb42e48b7175ccfabd887dc3ebb80a1697139e7
Cr-Commit-Position: refs/heads/master@{#404308}