Call setPosition with valid offset in another layout test.

Call setPosition with valid offset in another layout test.

Some layout tests call setPosition(node, offset) with large |offset| which is larger than |node|'s length but it is invalid in the standard:
https://dvcs.w3.org/hg/editing/raw-file/tip/editing.html#dom-selection-collapse

A typically case is that, image following HTML:
<div>text</div>
if you want to set a caret to between 'x' and 't', you should call Selection.setPostion(div.firstChild, 3).
However, many layout tests call Selection.setPosition(div, 3), which is invalid.
Many of those tests want to just set a caret to a last position of the node so this CL changes to call setPosition(node, node.childNodes.length).

I'm going to change Selection.setPosition to throw an exception for such a invalid call through Range.setStart/End.

This CL is similar to previous one:
https://src.chromium.org/viewvc/blink?revision=173167&view=revision

BUG=

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=173629

[Yuta Kitamura, 2014-05-08 08:47:07]

lgtm

[yoichio, 2014-05-08 08:49:14]

The CQ bit was checked by yoichio@chromium.org

[commit-bot: I haz the power, 2014-05-08 08:49:59]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/yoichio@chromium.org/272703007/1

[commit-bot: I haz the power, 2014-05-08 10:00:03]

Change committed as 173629