[CSS Grid Layout] Do log(n) search in the named line vectors when positioning named line spans

[CSS Grid Layout] Do log(n) search in the named line vectors when positioning named line spans

Implement the suggested FIXMEs and do a log search in the named line
vectors. This maintains the previous (somewhat tricky) behavior by
using std::lower_bound and std::upper_bound. No difference in existing
performance tests, but should scale much better for big grids.

BUG=303217
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=160187

[Julien - ping for review, 2013-10-18 14:19:43]

lgtm

[commit-bot: I haz the power, 2013-10-18 14:19:58]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xan@igalia.com/28823002/1

[commit-bot: I haz the power, 2013-10-18 21:17:19]

Retried try job too often on win_blink_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_blink_...

[commit-bot: I haz the power, 2013-10-21 15:51:25]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xan@igalia.com/28823002/1

[commit-bot: I haz the power, 2013-10-21 18:03:31]

Retried try job too often on win_blink_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_blink_...

[commit-bot: I haz the power, 2013-10-22 07:24:32]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/xan@igalia.com/28823002/1

[commit-bot: I haz the power, 2013-10-22 11:29:12]

Change committed as 160187