[es6] Reintroduce the instanceof operator in the backends.

src/crankshaft/arm/lithium-codegen-arm.cc

Index: src/crankshaft/arm/lithium-codegen-arm.cc
diff --git a/src/crankshaft/arm/lithium-codegen-arm.cc b/src/crankshaft/arm/lithium-codegen-arm.cc
index 0967cf276afcfec57f29acc59f2186f48d965294..a87e56a7b0d96d73bda84b551470970b72ec89c3 100644
--- a/src/crankshaft/arm/lithium-codegen-arm.cc
+++ b/src/crankshaft/arm/lithium-codegen-arm.cc
@@ -2494,16 +2494,6 @@ void LCodeGen::DoCmpMapAndBranch(LCmpMapAndBranch* instr) {
 }
 
 
-void LCodeGen::DoInstanceOf(LInstanceOf* instr) {
-  DCHECK(ToRegister(instr->context()).is(cp));
-  DCHECK(ToRegister(instr->left()).is(InstanceOfDescriptor::LeftRegister()));
-  DCHECK(ToRegister(instr->right()).is(InstanceOfDescriptor::RightRegister()));
-  DCHECK(ToRegister(instr->result()).is(r0));
-  InstanceOfStub stub(isolate());
-  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
-}
-
-
 void LCodeGen::DoHasInPrototypeChainAndBranch(
     LHasInPrototypeChainAndBranch* instr) {
   Register const object = ToRegister(instr->object());