MIPS: Add a trap_on_abort flag.

Port r16319 (22e0380)

Original commit message:
By setting this flag assertions behind --debug-code will trigger a
breakpoint instead of a call into Abort. This eases debugging, as the
call site is less cluttered and the backtrace starts where it should.

BUG=

Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16342 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/macro-assembler-mips.cc

@@ -4477,6 +4477,11 @@ void MacroAssembler::Abort(BailoutReason reason) {
     RecordComment("Abort message: ");
     RecordComment(msg);
   }
+
+  if (FLAG_trap_on_abort) {
+    stop(msg);
+    return;
+  }
 #endif
 
   li(a0, Operand(p0));