MIPS: small test-case fix for chaining of fixup position.

MIPS: small test-case fix for chaining of fixup position.

Add nops to the branch-delay slots of the 'beq' and 'bne' instructions
used in the test-case. Having a branch instruction in the branch-delay-slot
of another branch is undefined on mips.

In regular code we avoid this by using the Branch() macro-instruction which
fills the branch-delay-slot with nop() automatically, unless the programmer
asks to use it (via USE_BRANCH_DELAY).

There is more info about branch-delay-slots on this page, and in the ISA
reference also on the page:

https://github.com/paul99/v8m-rb/wiki/MIPS-instruction-set-and-v8

BUG=
TEST=
Committed: http://code.google.com/p/v8/source/detail?r=9079

[Sven Panne, 2011-08-31 09:17:39]

LGTM. Note that this patch is not really necessary, because we never execute the
machine code in these kind of tests, we do not even create a Code object. We
just need a forward reference to a label in the first instruction and another
forward reference later to test bind's behavior for this edge case. Anyway, I'll
land it to improve the code's esthetics... ;-)