MIPS: More OStreamsUse OStreams more often.

Port r22232 (f837b91)

Original commit message:
This is a mostly mechanical CL (more than 90% Emacs macros and
query-replace-regexp) moving FILE*/StringStream*-based APIs to
OStream-based APIs. There are a few places where this had to stop,
otherwise the CL would be even bigger, but this can easily and
incrementally cleaned up later.

BUG=
R=palfia@homejinni.com

Review URL: https://codereview.chromium.org/373773002

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@22250 ce2b1a6d-e550-0410-aec6-3dcde31c8c00