Upgrade Blink to milliseconds-based last modified filetimes, part 7.

Upgrade Blink to milliseconds-based last modified filetimes, part 7.

Remove WebFileInfo::modificationTimeMS, it is unused.

This completes the transition of WebFileInfo::modificationTime to be
milliseconds-based, and is the last patch in this series:

1: [blink] add WebFileInfo::modificationTimeMS [ https://codereview.chromium.org/873723004/ ]
2: [chromium] fill in modificationTimeMS [ https://codereview.chromium.org/884413002/ ] 
3: [blink] make use of modificationTimeMS [ https://codereview.chromium.org/884393002/ ]
4: [chromium] set modificationTime to something msec-based [ https://codereview.chromium.org/862203003/ ]
5: [blink] switch to modificationTime [ https://codereview.chromium.org/882343002/ ]
6: [chromium] stop setting modificationTimeMS [ https://codereview.chromium.org/890523002/ ]
7: [blink] *this one* [ https://codereview.chromium.org/869613005/ ]

R=mkwst
BUG=451747
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=189901

[Mike West, 2015-01-30 08:19:10]

mkwst@chromium.org changed reviewers:
+ mkwst@chromium.org

[Mike West, 2015-01-30 08:19:11]

LGTM \o/

[sof, 2015-02-10 12:53:05]

On 2015/01/30 08:19:11, Mike West wrote:
> LGTM \o/

Thanks all :) Let's do that again..hmm, maybe not.

[sof, 2015-02-10 12:53:10]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2015-02-10 12:53:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/869613005/1

[commit-bot: I haz the power, 2015-02-10 14:06:15]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=189901