Remove need to instantiate Platform and make methods static.

Remove need to instantiate Platform and make methods static.

This will require an update of the stable test binary. I will upload
a new build when done with the review process.

R=sgjesse@google.com
BUG=
TEST=

Committed: https://code.google.com/p/dart/source/detail?r=6682

[Søren Gjesse, 2012-04-18 11:17:42]

LGTM

Looks mush nicer!

[Sean Eagan, 2012-04-18 13:34:52]

Just wanted to point out that http://dartbug.com/1668 also mentions changing the
Platform methods to getters per the style guide, and it seems like it would make
sense to make that breaking change simultaneously to this one so people don't
have to fix their code twice.

[Mads Ager (google), 2012-04-18 14:11:53]

Thanks for the pointer Sean. I wasn't even aware of the bug because it was under
another category. I'll move it to Area-IO and consider if we should change these
to getters.