Create temp directory for sdk inside the dart directory.

Create temp directory for sdk inside the dart directory.
Committed: https://code.google.com/p/dart/source/detail?r=13957

[ahe, 2012-10-23 12:52:03]

lgtm

[dgrove, 2012-10-23 13:31:36]

On 2012/10/23 12:52:03, ahe wrote:
> lgtm

this looks fine, but i'm wondering what caused it to be needed.

[ahe, 2012-10-23 14:18:34]

dart2js-safari-mac ran out of disk space on / (root).

The temp directory on the mac builders is on the same FS as / (root). So if you
create a temporary directory in temp and don't delete it, you eventually run out
of disk space.

One of the things that create stuff in temp is create_sdk.py. This rules out one
source of the overflowing root file system. We are not pointing fingers, because
Safari is also filling up /, (through /Users/build-bot/Library/Caches).

Unfortunately, the build bot was rebooted before we had a chance to analyze the
root cause.