MIPS: port Fix ARM regression introduced with polymorphic array support.

src/mips/macro-assembler-mips.cc

Index: src/mips/macro-assembler-mips.cc
diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index 7c085baac0d8e494eedbaf63e114fd5e3fedf594..a8573d624eec9e5b4712945b584e081306e15806 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -2804,7 +2804,7 @@ void MacroAssembler::CheckFastElements(Register map,
                                        Register scratch,
                                        Label* fail) {
   STATIC_ASSERT(JSObject::FAST_ELEMENTS == 0);
-  lbu(scratch, FieldMemOperand(map, Map::kInstanceTypeOffset));
+  lbu(scratch, FieldMemOperand(map, Map::kBitField2Offset));
   Branch(fail, hi, scratch, Operand(Map::kMaximumBitField2FastElementValue));
 }