[es6] Reintroduce the instanceof operator in the backends.

src/crankshaft/ia32/lithium-codegen-ia32.cc

Index: src/crankshaft/ia32/lithium-codegen-ia32.cc
diff --git a/src/crankshaft/ia32/lithium-codegen-ia32.cc b/src/crankshaft/ia32/lithium-codegen-ia32.cc
index 15f79f75cb783c0d90cdbebc989b50004ce7e2c1..b1bcbd49ff132b0900ff3bdf066631935794b78a 100644
--- a/src/crankshaft/ia32/lithium-codegen-ia32.cc
+++ b/src/crankshaft/ia32/lithium-codegen-ia32.cc
@@ -2287,16 +2287,6 @@ void LCodeGen::DoCmpMapAndBranch(LCmpMapAndBranch* instr) {
 }
 
 
-void LCodeGen::DoInstanceOf(LInstanceOf* instr) {
-  DCHECK(ToRegister(instr->context()).is(esi));
-  DCHECK(ToRegister(instr->left()).is(InstanceOfDescriptor::LeftRegister()));
-  DCHECK(ToRegister(instr->right()).is(InstanceOfDescriptor::RightRegister()));
-  DCHECK(ToRegister(instr->result()).is(eax));
-  InstanceOfStub stub(isolate());
-  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
-}
-
-
 void LCodeGen::DoHasInPrototypeChainAndBranch(
     LHasInPrototypeChainAndBranch* instr) {
   Register const object = ToRegister(instr->object());