[turbofan] Introduce LoadFunctionPrototype simplified operator.

src/compiler/simplified-operator.h

Index: src/compiler/simplified-operator.h
diff --git a/src/compiler/simplified-operator.h b/src/compiler/simplified-operator.h
index 833a0554f588b11dc3af3f85c16223fa61c32d1e..c21b97dc31597ffbb289e28e32f2a7007f24f320 100644
--- a/src/compiler/simplified-operator.h
+++ b/src/compiler/simplified-operator.h
@@ -390,6 +390,9 @@ class V8_EXPORT_PRIVATE SimplifiedOperatorBuilder final
   // store-typed-element buffer, [base + external + index], value
   const Operator* StoreTypedElement(ExternalArrayType const&);
 
+  // load-function-prototype function
+  const Operator* LoadFunctionPrototype();
+
  private:
   Zone* zone() const { return zone_; }