[turbofan] Introduce LoadFunctionPrototype simplified operator.

src/compiler/simplified-lowering.cc

Index: src/compiler/simplified-lowering.cc
diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index 9e1cc7b5a29516fcef4280564048fc68f5aea16e..519a9e63741fa2ac335d71449f597c9c962eb336 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -2385,6 +2385,12 @@ class RepresentationSelector {
         SetOutput(node, MachineRepresentation::kNone);
         return;
       }
+      case IrOpcode::kLoadFunctionPrototype: {
+        if (truncation.IsUnused()) return VisitUnused(node);
+        VisitUnop(node, UseInfo::AnyTagged(),
+                  MachineRepresentation::kTaggedPointer);
+        return;
+      }
       case IrOpcode::kPlainPrimitiveToNumber: {
         if (InputIs(node, Type::Boolean())) {
           VisitUnop(node, UseInfo::Bool(), MachineRepresentation::kWord32);