MIPS: Optimize DoCheckMaps.

This simple change moves the Deoptimize call into the Deopt table
where it belongs, and shortens the inline map-check.

Gives a surprisingly large performance gain, around 4% on Octane.

BUG=
R=gergely@homejinni.com

Review URL: https://codereview.chromium.org/22391008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@16115 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/lithium-codegen-mips.cc

@@ -5253,11 +5253,11 @@ void LCodeGen::DoCheckMaps(LCheckMaps* instr) {
     __ CompareMapAndBranch(map_reg, map, &success, eq, &success);
   }
   Handle<Map> map = map_set->last();
-  __ CompareMapAndBranch(map_reg, map, &success, eq, &success);
+  // Do the CompareMap() directly within the Branch() and DeoptimizeIf().
   if (instr->hydrogen()->has_migration_target()) {
-    __ Branch(deferred->entry());
+    __ Branch(deferred->entry(), ne, map_reg, Operand(map));
   } else {
-    DeoptimizeIf(al, instr->environment());
+    DeoptimizeIf(ne, instr->environment(), map_reg, Operand(map));
   }
 
   __ bind(&success);