Revert of Fixit: Factor out common base::Time* math operator overloads.

Revert of Fixit: Factor out common base::Time* math operator overloads. (patchset #2 id:40001 of https://codereview.chromium.org/1122443004/)

Reason for revert:
Broke iOS build.

http://build.chromium.org/p/chromium.mac/builders/iOS_Device/builds/5621/steps/compile/logs/stdio

Original issue's description:
> Fixit: Factor out common base::Time* math operator overloads.
>
> This is part 1 of a 2-part change to fork base::TimeTicks into three
> type-checked time classes (TimeTicks + ThreadTicks + TraceTicks).  The
> forking of TimeTicks will ensure values from different clocks are not
> erroneously being mixed together when doing time math.
>
> In this change, the identical comparison and math operator overloads
> found in base::Time and base::TimeTicks are being factored-out into a
> templated base class.  In a following change, this base class will also
> be used to de-dupe this common functionality in the two new time
> classes.
>
> BUG=467417
>
> Committed: https://crrev.com/7ca717095b4758cb76e53e904b775852e46d646d
> Cr-Commit-Position: refs/heads/master@{#328696}

TBR=thestig@chromium.org,miu@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=467417
Committed: https://crrev.com/a365825583412c355a449274bec70e41e992ffd7
Cr-Commit-Position: refs/heads/master@{#328706}

[Kunihiko Sakamoto, 2015-05-07 04:32:37]

Created Revert of Fixit: Factor out common base::Time* math operator overloads.

[commit-bot: I haz the power, 2015-05-07 04:34:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1130953002/1

[commit-bot: I haz the power, 2015-05-07 04:35:31]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-07 04:36:37]

Patchset 1 (id:??) landed as
https://crrev.com/a365825583412c355a449274bec70e41e992ffd7
Cr-Commit-Position: refs/heads/master@{#328706}

[miu, 2015-05-07 04:56:29]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1128273004/ by miu@chromium.org.

The reason for reverting is: DO NOT COMMIT.