Get rid of the HInstanceSize instruction.

src/mips/lithium-codegen-mips.cc

Index: src/mips/lithium-codegen-mips.cc
diff --git a/src/mips/lithium-codegen-mips.cc b/src/mips/lithium-codegen-mips.cc
index 38b0ff5274d4c44cda241072aa8e7a7ab05a54be..7e8f9582edacc2b01f0be9fb713c7ad05ab88f16 100644
--- a/src/mips/lithium-codegen-mips.cc
+++ b/src/mips/lithium-codegen-mips.cc
@@ -2745,14 +2745,6 @@ void LCodeGen::DoDeferredInstanceOfKnownGlobal(LInstanceOfKnownGlobal* instr,
 }
 
 
-void LCodeGen::DoInstanceSize(LInstanceSize* instr) {
-  Register object = ToRegister(instr->object());
-  Register result = ToRegister(instr->result());
-  __ lw(result, FieldMemOperand(object, HeapObject::kMapOffset));
-  __ lbu(result, FieldMemOperand(result, Map::kInstanceSizeOffset));
-}
-
-
 void LCodeGen::DoCmpT(LCmpT* instr) {
   ASSERT(ToRegister(instr->context()).is(cp));
   Token::Value op = instr->op();