[Line Layout API] Convert most of InlineBoxPainter to new API

[Line Layout API] Convert most of InlineBoxPainter to new API

This CL adds two necessary methods to the line layout API and updates callers
to use them.

1. LineLayoutBoxModel::boxShadowShouldBeAppliedToBackground
2. LineLayoutItem::enclosingBoxModelObject (implemented in LineLayoutBoxModel.h
   to avoid pulling LayoutBoxModel into LineLayoutItem)

BUG=499321
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=201013

[pilgrim_google, 2015-08-21 14:46:46]

pilgrim@chromium.org changed reviewers:
+ jsbell@chromium.org, leviw@chromium.org, ojan@chromium.org

[leviw_travelin_and_unemployed, 2015-08-21 18:37:14]

lgtm

https://codereview.chromium.org/1303303002/diff/1/Source/core/layout/api/Line...
File Source/core/layout/api/LineLayoutItem.h (right):

https://codereview.chromium.org/1303303002/diff/1/Source/core/layout/api/Line...
Source/core/layout/api/LineLayoutItem.h:70: // Intentionally returns a BoxModel
to avoid exposing LayoutBoxModelObject
Intentionally returns LineLayoutBoxModel

[pilgrim_google, 2015-08-21 19:08:22]

The CQ bit was checked by pilgrim@chromium.org

[pilgrim_google, 2015-08-21 19:08:22]

The patchset sent to the CQ was uploaded after l-g-t-m from leviw@chromium.org
Link to the patchset: https://codereview.chromium.org/1303303002/#ps20001
(title: "nits")

[commit-bot: I haz the power, 2015-08-21 19:08:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1303303002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1303303002/20001

[commit-bot: I haz the power, 2015-08-21 21:10:59]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=201013