Allow explicit navigations to "0.0.0.0" to support systems where this performs a

Allow explicit navigations to "0.0.0.0" to support systems where this performs a
navigation to localhost (in defiance of specs... but seemingly common).

This still prevents navigation to any other IP with leading octet 0, and only
allows 0.0.0.0 when it's actually entered in 4-component dotted-quad form.

BUG=428046
TEST=Entering "0.0.0.0" in the address bar will navigate by default

Committed: https://crrev.com/65e7a0403eb51c8490ee13e5da3ed8e544c34926
Cr-Commit-Position: refs/heads/master@{#323946}

[Peter Kasting, 2015-04-03 21:44:49]

pkasting@chromium.org changed reviewers:
+ mpearson@chromium.org

[Mark P, 2015-04-06 18:31:29]

lgtm

[Peter Kasting, 2015-04-06 19:25:25]

The CQ bit was checked by pkasting@chromium.org

[commit-bot: I haz the power, 2015-04-06 19:26:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1064453002/1

[commit-bot: I haz the power, 2015-04-06 21:02:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-06 21:04:47]

Patchset 1 (id:??) landed as
https://crrev.com/65e7a0403eb51c8490ee13e5da3ed8e544c34926
Cr-Commit-Position: refs/heads/master@{#323946}