[turbofan] First step towards sanitizing for-in and making it optimizable.

src/compiler/js-operator.h

Index: src/compiler/js-operator.h
diff --git a/src/compiler/js-operator.h b/src/compiler/js-operator.h
index 3678658de88794bf3904b6bfcf84159215b1ce7e..ae26665b2eb45344ca38d36ba0cf5e2e02e62a3b 100644
--- a/src/compiler/js-operator.h
+++ b/src/compiler/js-operator.h
@@ -300,6 +300,11 @@ class JSOperatorBuilder final : public ZoneObject {
   const Operator* TypeOf();
   const Operator* InstanceOf();
 
+  const Operator* ForInDone();
+  const Operator* ForInNext();
+  const Operator* ForInPrepare();
+  const Operator* ForInStep();
+
   const Operator* StackCheck();
 
   // TODO(titzer): nail down the static parts of each of these context flavors.