X87: [es6] Reintroduce the instanceof operator in the backends.

src/crankshaft/x87/lithium-x87.cc

Index: src/crankshaft/x87/lithium-x87.cc
diff --git a/src/crankshaft/x87/lithium-x87.cc b/src/crankshaft/x87/lithium-x87.cc
index 830c6d5bf1259c0d9619d4b56fc6f317f89a578e..7df70ae21f1066e5217425a64fec4335c61a7c77 100644
--- a/src/crankshaft/x87/lithium-x87.cc
+++ b/src/crankshaft/x87/lithium-x87.cc
@@ -983,17 +983,6 @@ LInstruction* LChunkBuilder::DoArgumentsElements(HArgumentsElements* elems) {
 }
 
 
-LInstruction* LChunkBuilder::DoInstanceOf(HInstanceOf* instr) {
-  LOperand* left =
-      UseFixed(instr->left(), InstanceOfDescriptor::LeftRegister());
-  LOperand* right =
-      UseFixed(instr->right(), InstanceOfDescriptor::RightRegister());
-  LOperand* context = UseFixed(instr->context(), esi);
-  LInstanceOf* result = new (zone()) LInstanceOf(context, left, right);
-  return MarkAsCall(DefineFixed(result, eax), instr);
-}
-
-
 LInstruction* LChunkBuilder::DoHasInPrototypeChainAndBranch(
     HHasInPrototypeChainAndBranch* instr) {
   LOperand* object = UseRegister(instr->object());