Make Blink support multiline text insertion

Make Blink support multiline text insertion

When inserting multiline text, Blink will insert the text before '\n' and the
text after the '\n' separately, e.g., for "hello\nworld", Blink will insert
"hello", then a paragraph separator, then "world".

However, after inserting "hello", the text is updated to "hello" incorrectly,
so the remaining "world" will not be inserted. This CL moves the
text-updating logic to upper level to make it right. Besides, this CL adjusts
the selection after each insertion for incremental insertion.

BUG=683885
Review-Url: https://codereview.chromium.org/2680733002
Cr-Commit-Position: refs/heads/master@{#448920}
(cherry picked from commit 286c2ce88f848617aff81090e9cc41afdf5de7e5)

Review-Url: https://codereview.chromium.org/2691433002 .
Cr-Commit-Position: refs/branch-heads/2987@{#422}
Cr-Branched-From: ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed: https://chromium.googlesource.com/chromium/src/+/51c86d6f3e40a86b4fb2d8a08442b808ccfa8a1e

[aelias_OOO_until_Jul13, 2017-02-09 23:20:56]

Description was changed from

==========
Make Blink support multiline text insertion

When inserting multiline text, Blink will insert the text before '\n' and the
text after the '\n' separately, e.g., for "hello\nworld", Blink will insert
"hello", then a paragraph separator, then "world".

However, after inserting "hello", the text is updated to "hello" incorrectly,
so the remaining "world" will not be inserted. This CL moves the
text-updating logic to upper level to make it right. Besides, this CL adjusts
the selection after each insertion for incremental insertion.

BUG=683885

Review-Url: https://codereview.chromium.org/2680733002
Cr-Commit-Position: refs/heads/master@{#448920}
(cherry picked from commit 286c2ce88f848617aff81090e9cc41afdf5de7e5)
==========

to

==========
Make Blink support multiline text insertion

When inserting multiline text, Blink will insert the text before '\n' and the
text after the '\n' separately, e.g., for "hello\nworld", Blink will insert
"hello", then a paragraph separator, then "world".

However, after inserting "hello", the text is updated to "hello" incorrectly,
so the remaining "world" will not be inserted. This CL moves the
text-updating logic to upper level to make it right. Besides, this CL adjusts
the selection after each insertion for incremental insertion.

BUG=683885

Review-Url: https://codereview.chromium.org/2680733002
Cr-Commit-Position: refs/heads/master@{#448920}
(cherry picked from commit 286c2ce88f848617aff81090e9cc41afdf5de7e5)

Review-Url: https://codereview.chromium.org/2691433002 .
Cr-Commit-Position: refs/branch-heads/2987@{#422}
Cr-Branched-From:
ad51088c0e8776e8dcd963dbe752c4035ba6dab6-refs/heads/master@{#444943}
Committed:
https://chromium.googlesource.com/chromium/src/+/51c86d6f3e40a86b4fb2d8a08442...
==========

[aelias_OOO_until_Jul13, 2017-02-09 23:20:57]

Committed patchset #1 (id:1) manually as
51c86d6f3e40a86b4fb2d8a08442b808ccfa8a1e.