Put the parentheses back where they belong in time_mac.cc

Put the parentheses back where they belong in time_mac.cc. This will allow
Aaron's new test in http://codereview.chromium.org/4471001 to pass.

BUG=49233
TEST=base_unittests Time.FromExplodedWithMilliseconds from
     http://codereview.chromium.org/4471001

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=66174

[Mark Mentovai, 2010-11-15 21:11:27]

This was correct when I initially wrote it, but someone added some parentheses
in the wrong place.

FYI: CFGregorianDate supports sub-second precision, because internally it’s all
based on floating-point “double” values. Precision gradually degrades as you
move further from the epoch, but 500ms precision should be attainable for all
practical times. The bug here was that values would get truncated down to int,
so any sub-second data would get lost. FromExploded was actually fine, the only
bug was in Explode.

[Aaron Boodman, 2010-11-15 21:27:45]

Awesome. LGTM.

[Aaron Boodman, 2010-11-15 21:28:33]

Do you want to submit this? If so, you should put my test into this CL so they
go together. Otherwise, I'll submit this change with my CL and the test all at
the same time.

[Mark Mentovai, 2010-11-15 21:39:33]

Yeah, I submitted this one because it works as a standalone. Your test
should pass on the Mac when you add it now.