Replace Selection.collapse() with Selection.removeAllRanges() in layout tests..

Replace Selection.collapse() with Selection.removeAllRanges() in layout tests.

There are some tests calling Selection.collapse(null).
Selection.collapse(null) clears the current selection and its behavior is essentially same as Selection.removeAllRanges().
However, the Selection.collapse method is intended to create a range forming a caret:
https://dvcs.w3.org/hg/editing/raw-file/tip/editing.html#dom-selection-collapse
Calling Selection.collapse(null) to clear the selection is non-standard and I'm going to change Selection.idl to restrict such a usage.

BUG=361941
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=171436

[yosin_UTC9, 2014-04-14 04:41:05]

ACK
Thanks for cleanup!

[Yuta Kitamura, 2014-04-14 06:18:27]

The CL itself LGTM but the change description text has a great room of
improvement.

> Current tests calling Selection.collapse(null) depend on tricky Blink 
> behavior and Selection.collapse(null) is also not specified. 
> Hence we should rewrite them. 
> Selection.collapse(null) behave is virtually same as
Selection.removeAllRanges() in Blink. 
> Thus we can replace Selection.collapse with Selection.removeAllRanges. 

I think the biggest issue in this change description is that you failed to
mention that you are going to fix Selection.collapse() behavior, which is vital
to understand the motivation of this change.

You probably need to rewrite the change description with the following points
in mind:
- Some tests are using Selection.collapse(null)
- It clears the current selection, which is essentially same as
  removeAllRanges()
- This behavior is non-standard
- You are going to fix Selection.collapse() implementation, which will break
  these tests
- The motivation of this change is to fix these tests before you fix
  Selection.collapse() behavior

Please be sure to organize your change description so people without much
context can understand the motivation of your change.

A nitpick on the original text:
"behave" -> "behavior"

[yoichio, 2014-04-14 06:53:37]

The CQ bit was checked by yoichio@chromium.org

[commit-bot: I haz the power, 2014-04-14 06:53:47]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/yoichio@chromium.org/236693002/1

[commit-bot: I haz the power, 2014-04-14 07:53:50]

Change committed as 171436