[InputEvent] Add null check before converting Range to StaticRange

[InputEvent] Add null check before converting Range to StaticRange

It's possible for |firstRangeOf()| to return null (see test case), and we shouldn't try to
construct StaticRange in this case.

BUG=697319
Review-Url: https://codereview.chromium.org/2727293003
Cr-Commit-Position: refs/heads/master@{#454614}
(cherry picked from commit b05824d69f2a8403552ef9e29bebdece24005400)

Review-Url: https://codereview.chromium.org/2763833006 .
Cr-Commit-Position: refs/branch-heads/3029@{#356}
Cr-Branched-From: 939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed: https://chromium.googlesource.com/chromium/src/+/f79755f945b6cee034ecc5085d7f7ae214251f8f

[chongz, 2017-03-22 16:01:30]

Description was changed from

==========
[InputEvent] Add null check before converting Range to StaticRange

It's possible for |firstRangeOf()| to return null (see test case), and we
shouldn't try to
construct StaticRange in this case.

BUG=697319

Review-Url: https://codereview.chromium.org/2727293003
Cr-Commit-Position: refs/heads/master@{#454614}
(cherry picked from commit b05824d69f2a8403552ef9e29bebdece24005400)
==========

to

==========
[InputEvent] Add null check before converting Range to StaticRange

It's possible for |firstRangeOf()| to return null (see test case), and we
shouldn't try to
construct StaticRange in this case.

BUG=697319

Review-Url: https://codereview.chromium.org/2727293003
Cr-Commit-Position: refs/heads/master@{#454614}
(cherry picked from commit b05824d69f2a8403552ef9e29bebdece24005400)

Review-Url: https://codereview.chromium.org/2763833006 .
Cr-Commit-Position: refs/branch-heads/3029@{#356}
Cr-Branched-From:
939b32ee5ba05c396eef3fd992822fcca9a2e262-refs/heads/master@{#454471}
Committed:
https://chromium.googlesource.com/chromium/src/+/f79755f945b6cee034ecc5085d7f...
==========

[chongz, 2017-03-22 16:01:32]

Committed patchset #1 (id:1) manually as
f79755f945b6cee034ecc5085d7f7ae214251f8f.