SI-7473 Bad for expr crashes postfix

This commit makes building PostfixSelect robust against a bad pos
on its operand, which can happen if a bad for expression results
in an EmptyTree.
SI-7497 Fix scala.util.Properties.isMac

It returned wrong values because it used the java.vendor
property instead of os.name.

See http://mail.openjdk.java.net/pipermail/macosx-port-dev/2012-November/005148.html
for the reason why we don't follow developer.apple.com/library/mac/#technotes/tn2002/tn2110.
Merge pull request #2559 from soc/SI-7497

SI-7497 Fix scala.util.Properties.isMac
SI-7421 remove unneeded extra-attachement in maven deploy
Merge pull request #2595 from adriaanm/backport-pr-2450

SI-7421 remove unneeded extra-attachement in maven deploy
A test case for a recent LUB progression.

A test distilled from a Lift example that compiles correctly
under 2.10.1, but not under 2.10.0.

I pinpointed the progression to:

  https://github.com/scala/scala/commit/a06d31f6#L0R6611

Chalk up another win for `dealiasWiden`.
Merge pull request #2600 from retronym/topic/lub-dealias-widen

A test case for a recent LUB progression.
Merge pull request #2583 from som-snytt/issue/7473-pointless-for-crash

SI-7473 Bad for expr crashes postfix