MIPS: Add tool to visualize machine code/lithium.

MIPS: Add tool to visualize machine code/lithium.

Port r17295 (b36eb655)

Original commit message:
In the process:
- Add a command-line flag --opt-code-positions to track source position information throughout optimized code.
- Add a subclass of the hydrogen graph builder to ensure that the source position is properly set on the graph builder for all generated hydrogen code.
- Overhaul handling of source positions in hydrogen to ensure they are passed through to generated code consistently and in most cases transparently.

BUG=
R=plind44@gmail.com

Committed: https://code.google.com/p/v8/source/detail?r=17305

[palfia, 2013-10-21 21:39:44]

PTAL.

[Paul Lind, 2013-10-21 22:17:51]

LGTM. I did notice an odd thing in CallCodeGeneric(), but it is unrelated to
this change, so let's commit this. I will followup with you offline if we need
to do another CL there.

[palfia, 2013-10-21 22:20:53]

Committed patchset #1 manually as r17305 (presubmit successful).