[turbofan] First steps towards optimizing for-in loops.

src/compiler/js-typed-lowering.h

Index: src/compiler/js-typed-lowering.h
diff --git a/src/compiler/js-typed-lowering.h b/src/compiler/js-typed-lowering.h
index 6533773fa831ff793aeea3c11138bfd9e1cb41a6..64931e1a0105774566749e0506e192ba2af25715 100644
--- a/src/compiler/js-typed-lowering.h
+++ b/src/compiler/js-typed-lowering.h
@@ -58,6 +58,10 @@ class JSTypedLowering final : public AdvancedReducer {
   Reduction ReduceJSCreateLiteralObject(Node* node);
   Reduction ReduceJSCreateWithContext(Node* node);
   Reduction ReduceJSCreateBlockContext(Node* node);
+  Reduction ReduceJSForInDone(Node* node);
+  Reduction ReduceJSForInNext(Node* node);
+  Reduction ReduceJSForInPrepare(Node* node);
+  Reduction ReduceJSForInStep(Node* node);
   Reduction ReduceNumberBinop(Node* node, const Operator* numberOp);
   Reduction ReduceInt32Binop(Node* node, const Operator* intOp);
   Reduction ReduceUI32Shift(Node* node, Signedness left_signedness,