Build for Mac in the Release configuration at -O2

Build for Mac in the Release configuration at -O2

BUG=16713
TEST=Watch perf.  Startup time should be flat or possibly lose a very small
         amount (~1%).  Everything else should be a little bit faster.
     Watch sizes.  The .app and .dmg will grow, but I've cut their sizes way
         down lately, and I'd like to cash in some of those gains for speed.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=23882

[Mark Mentovai, 2009-08-20 20:14:51]

-O2 ought to be a perf winner.  We might even be able to get away with -O3.  I'd
like to try this for a few days, and also experiment with -O3, to see if there's
a clear advantage to one over the other.

In my own tests, this is a win over -Os.  I actually spent a lot of time
benchmarking V8, and -Os seemed to be even slower than -O1 for that workload. 
Separately, we'll build V8 at -O3 the next time we get a new version of it.

There will be an .app and .dmg size hit.  The .dmg will grow by about 0.75 MB.

The startup time impact will be flat, or will perhaps increase by no more than
5ms.  I think that this is tolerable, given the huge strides we've made in Ts
performance recently.  We've managed to recover 140ms.  Go team!  I also think
that the run-time boost that this will give us is worth 5ms at startup.

The stuff in common.gypi that's moving around is mostly infrastructural stuff to
make sure that this change plays nicely with V8 using -O3.

The DEPS change is to pick up a Breakpad fix: due to differing optimization, the
compiler caught an error in Breakpad at -O2 that it wasn't catching at -O0 or
-Os.

pink because he's here today, and TVL because he's not.

[pink (ping after 24hrs), 2009-08-20 20:38:23]

LGTM!

[TVL, 2009-08-24 12:36:14]

lgtm