[turbofan] Optimize JSConvertReceiver if we know something about the receiver.

src/compiler/js-operator.cc

Index: src/compiler/js-operator.cc
diff --git a/src/compiler/js-operator.cc b/src/compiler/js-operator.cc
index ad2369da92a460de60905aa5ddf8267b14eb25c3..36a3c436962c3292ac140f443637b5c50235a727 100644
--- a/src/compiler/js-operator.cc
+++ b/src/compiler/js-operator.cc
@@ -40,12 +40,12 @@ size_t hash_value(VectorSlotPair const& p) {
 }
 
 
-size_t hash_value(ConvertReceiverMode const& mode) {
+size_t hash_value(ConvertReceiverMode mode) {
   return base::hash_value(static_cast<int>(mode));
 }
 
 
-std::ostream& operator<<(std::ostream& os, ConvertReceiverMode const& mode) {
+std::ostream& operator<<(std::ostream& os, ConvertReceiverMode mode) {
   switch (mode) {
     case ConvertReceiverMode::kNullOrUndefined:
       return os << "NULL_OR_UNDEFINED";
@@ -59,6 +59,12 @@ std::ostream& operator<<(std::ostream& os, ConvertReceiverMode const& mode) {
 }
 
 
+ConvertReceiverMode ConvertReceiverModeOf(Operator const* op) {
+  DCHECK_EQ(IrOpcode::kJSConvertReceiver, op->opcode());
+  return OpParameter<ConvertReceiverMode>(op);
+}
+
+
 std::ostream& operator<<(std::ostream& os, CallFunctionParameters const& p) {
   os << p.arity() << ", " << p.flags() << ", " << p.language_mode();
   if (p.AllowTailCalls()) {