[runtime] Remove the redundant %_IsObject intrinsic.

src/full-codegen/mips/full-codegen-mips.cc

Index: src/full-codegen/mips/full-codegen-mips.cc
diff --git a/src/full-codegen/mips/full-codegen-mips.cc b/src/full-codegen/mips/full-codegen-mips.cc
index b39f698e4a8b5b39a958d0751efcba0f4d3af636..1834d09f9c78a31ce2167d904acbd2667b45d1b3 100644
--- a/src/full-codegen/mips/full-codegen-mips.cc
+++ b/src/full-codegen/mips/full-codegen-mips.cc
@@ -3362,37 +3362,6 @@ void FullCodeGenerator::EmitIsNonNegativeSmi(CallRuntime* expr) {
 }
 
 
-void FullCodeGenerator::EmitIsObject(CallRuntime* expr) {
-  ZoneList<Expression*>* args = expr->arguments();
-  DCHECK(args->length() == 1);
-
-  VisitForAccumulatorValue(args->at(0));
-
-  Label materialize_true, materialize_false;
-  Label* if_true = NULL;
-  Label* if_false = NULL;
-  Label* fall_through = NULL;
-  context()->PrepareTest(&materialize_true, &materialize_false,
-                         &if_true, &if_false, &fall_through);
-
-  __ JumpIfSmi(v0, if_false);
-  __ LoadRoot(at, Heap::kNullValueRootIndex);
-  __ Branch(if_true, eq, v0, Operand(at));
-  __ lw(a2, FieldMemOperand(v0, HeapObject::kMapOffset));
-  // Undetectable objects behave like undefined when tested with typeof.
-  __ lbu(a1, FieldMemOperand(a2, Map::kBitFieldOffset));
-  __ And(at, a1, Operand(1 << Map::kIsUndetectable));
-  __ Branch(if_false, ne, at, Operand(zero_reg));
-  __ lbu(a1, FieldMemOperand(a2, Map::kInstanceTypeOffset));
-  __ Branch(if_false, lt, a1, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));
-  PrepareForBailoutBeforeSplit(expr, true, if_true, if_false);
-  Split(le, a1, Operand(LAST_NONCALLABLE_SPEC_OBJECT_TYPE),
-        if_true, if_false, fall_through);
-
-  context()->Plug(if_true, if_false);
-}
-
-
 void FullCodeGenerator::EmitIsSpecObject(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   DCHECK(args->length() == 1);