Remove system-provided temporary directory usage from test scripts.

Remove system-provided temporary directory usage from test scripts.

BUG=
TEST=

Committed: https://code.google.com/p/dart/source/detail?r=7783

[Bill Hesse, 2012-05-16 14:56:17]

This is all dead code, because StubGenerator tests are gone, and dartc is not
running browser tests or generating code any more.

Any future tests should be able to make a directory in the build directory,
using the getOutputDirectory function that is already there.

[Bill Hesse, 2012-05-16 14:59:53]

This is all dead code, because StubGenerator tests are gone, and dartc is not
running browser tests or generating code any more.

Any future tests should be able to make a directory in the build directory,
using the getOutputDirectory function that is already there.

[Emily Fortuna, 2012-05-16 16:36:04]

lgtm. I just want to make sure -- the temporary html pages and compiled js that
is used for the browser tests doesn't use this code, right? (I didn't think so,
but just wanted to be certain)