MIPS: Followup to '[turbofan] Add basic support for calling to (a subset of) C functions.'

MIPS: Followup to '[turbofan] Add basic support for calling to (a subset of) C functions.'

Port a58ba8d80179bf5b6b7245590c82e47fda8c8a5e

Original commit message:
This introduces some initial building blocks for calling out to
C/C++ functions directly from TurboFan generated code objects.

BUG=

[paul.l..., 2015-06-26 04:58:41]

paul.lind@imgtec.com changed reviewers:
+ akos.palfi@imgtec.com, dusan.milosavljevic@imgtec.com, paul.lind@imgtec.com

[paul.l..., 2015-06-26 04:58:41]

I don't understand the motivation to move away from the range-based for loops in
https://codereview.chromium.org/1205023002/.

Note that he moved away only in the case of the Poke loops, where they used
MiscField::encode(slot). We do not use that, we use slot as an immediate value.
But we _do_ use slot for _both_ the the C-call and JS-call for loops. So my
opinion is that we should change both or neither.

Unless it is clear to you, you might want to ask via email.