Remove unittest-based wrapping from our testing scripts

Remove unittest-based wrapping from our testing scripts

The unittest-based wrapping of tests is completely broken and will be removed
with this CL. ('none-drt' is the last configuration where we currently still do
unittest-based wrapping.)

BUG=
R=ricow@google.com

Committed: https://code.google.com/p/dart/source/detail?r=28501

[kustermann, 2013-10-10 15:27:06]

We still have these small wrappers around main() to get the
'dart-calling-main'/'dart-main-done' messages -- eventually we also want to get
rid of them (but this is not a high priority).

[ricow1, 2013-10-11 07:43:52]

LGTM

[kustermann, 2013-10-11 09:01:24]

Committed patchset #1 manually as r28501 (presubmit successful).