Move computeInlineBoxPosition out from PositionAlgorithm class

Move computeInlineBoxPosition() out from PositionAlgorithm template class

This patch moves |computeInlineBoxPosition()| out from |PositionAlgorithm|
template class to reduce |InlineBox| dependency in |PositionAlgorithm| class
and simplify |PositionAlgorithm| class for improving code health.

Following patch will move |computeInlineBoxPosition()| to "VisibleUnits.cpp".

BUG=518738
TEST=n/a; no behavior changes

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200906

[yosin_UTC9, 2015-08-20 04:20:27]

The CQ bit was checked by yosin@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-20 04:20:36]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295893006/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295893006/1

[commit-bot: I haz the power, 2015-08-20 04:49:24]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-20 04:49:25]

Dry run: Try jobs failed on following builders:
  chromeos_daisy_chromium_compile_only_ng on tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromeos_daisy_...)

[yosin_UTC9, 2015-08-20 04:59:06]

On 2015/08/20 04:49:25, commit-bot: I haz the power wrote:
> Dry run: Try jobs failed on following builders:
>   chromeos_daisy_chromium_compile_only_ng on tryserver.chromium.linux
> (JOB_FAILED,
>
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromeos_daisy_...)

It seems android and chromeos bots are broken. They failed on compilation
without this patch.

[yosin_UTC9, 2015-08-20 05:01:18]

yosin@chromium.org changed reviewers:
+ hajimehoshi@chromium.org, yoichio@chromium.org

[yosin_UTC9, 2015-08-20 05:01:27]

PTAL

[hajimehoshi, 2015-08-20 05:27:42]

lgtm

[yoichio, 2015-08-20 05:44:26]

lgtm

[yosin_UTC9, 2015-08-20 08:25:49]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2015-08-20 08:25:55]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295893006/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295893006/1

[commit-bot: I haz the power, 2015-08-20 08:28:24]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-20 08:28:25]

Try jobs failed on following builders:
  chromeos_amd64-generic_chromium_compile_only_ng on tryserver.chromium.linux
(JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromeos_amd64-...)
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[yosin_UTC9, 2015-08-20 09:20:56]

The CQ bit was checked by yosin@chromium.org

[yosin_UTC9, 2015-08-20 09:20:57]

The patchset sent to the CQ was uploaded after l-g-t-m from
yoichio@chromium.org, hajimehoshi@chromium.org
Link to the patchset: https://codereview.chromium.org/1295893006/#ps20001
(title: "2015-08-20T18:19:45 Rebase")

[commit-bot: I haz the power, 2015-08-20 09:21:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295893006/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295893006/20001

[commit-bot: I haz the power, 2015-08-20 11:24:58]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-20 11:24:59]

Try jobs failed on following builders:
  win_chromium_rel_ng on tryserver.chromium.win (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_rel_...)

[yosin_UTC9, 2015-08-20 11:25:54]

The CQ bit was checked by yosin@chromium.org

[commit-bot: I haz the power, 2015-08-20 11:26:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295893006/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295893006/20001

[commit-bot: I haz the power, 2015-08-20 11:31:03]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-20 11:31:04]

Try jobs failed on following builders:
  chromium_presubmit on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)

[yosin_UTC9, 2015-08-20 13:32:20]

The CQ bit was checked by yosin@chromium.org

[yosin_UTC9, 2015-08-20 13:32:20]

The patchset sent to the CQ was uploaded after l-g-t-m from
yoichio@chromium.org, hajimehoshi@chromium.org
Link to the patchset: https://codereview.chromium.org/1295893006/#ps40001
(title: "2015-08-20T22:30:52 Rebase")

[commit-bot: I haz the power, 2015-08-20 13:32:32]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1295893006/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1295893006/40001

[commit-bot: I haz the power, 2015-08-20 15:34:50]

Committed patchset #3 (id:40001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200906