[Layout API] Use Document::layoutViewItem in WebFrameTest

[Layout API] Use Document::layoutViewItem in WebFrameTest

Document::layoutView() is deprecated and close to being removed
altogether. This CL migrates WebFrameTest to use the comparable
layoutViewItem() method. I had to add LayoutItem::mutableStyleRef() to
the block layout API.

There are no functional changes.

BUG=499321
Committed: https://crrev.com/7e21fa1d122ce05b3d121d8a520f8b5e9bc66dae
Cr-Commit-Position: refs/heads/master@{#402289}

[pilgrim_google, 2016-06-10 13:15:07]

pilgrim@chromium.org changed reviewers:
+ eae@chromium.org, jsbell@chromium.org, tkent@chromium.org

[pilgrim_google, 2016-06-10 13:15:07]

+tkent because web/

[tkent, 2016-06-12 23:13:34]

lgtm

[eae, 2016-06-21 09:19:25]

LGTM

[pilgrim_google, 2016-06-27 18:55:01]

The CQ bit was checked by pilgrim@chromium.org

[pilgrim_google, 2016-06-27 18:55:02]

The patchset sent to the CQ was uploaded after l-g-t-m from tkent@chromium.org,
eae@chromium.org
Link to the patchset: https://codereview.chromium.org/2053113003/#ps20001
(title: "rebase")

[commit-bot: I haz the power, 2016-06-27 18:55:35]

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, 2016-06-27 21:29:02]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2016-06-27 21:31:03]

Description was changed from

==========
[Layout API] Use Document::layoutViewItem in WebFrameTest

Document::layoutView() is deprecated and close to being removed
altogether. This CL migrates WebFrameTest to use the comparable
layoutViewItem() method. I had to add LayoutItem::mutableStyleRef() to
the block layout API.

There are no functional changes.

BUG=499321
==========

to

==========
[Layout API] Use Document::layoutViewItem in WebFrameTest

Document::layoutView() is deprecated and close to being removed
altogether. This CL migrates WebFrameTest to use the comparable
layoutViewItem() method. I had to add LayoutItem::mutableStyleRef() to
the block layout API.

There are no functional changes.

BUG=499321

Committed: https://crrev.com/7e21fa1d122ce05b3d121d8a520f8b5e9bc66dae
Cr-Commit-Position: refs/heads/master@{#402289}
==========

[commit-bot: I haz the power, 2016-06-27 21:31:04]

Patchset 2 (id:??) landed as
https://crrev.com/7e21fa1d122ce05b3d121d8a520f8b5e9bc66dae
Cr-Commit-Position: refs/heads/master@{#402289}