[stubs] Port LoadFunctionPrototypeStub to CSA

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 0e431293f108767bec1413cdccaed96614cba453..37220c3d26e8d9ef95692a371baf971de0009b96 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -4029,32 +4029,6 @@ void MacroAssembler::GetMapConstructor(Register result, Register map,
   bind(&done);
 }
 
-
-void MacroAssembler::TryGetFunctionPrototype(Register function, Register result,
-                                             Label* miss) {
-  // Get the prototype or initial map from the function.
-  movp(result,
-       FieldOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
-
-  // If the prototype or initial map is the hole, don't return it and
-  // simply miss the cache instead. This will allow us to allocate a
-  // prototype object on-demand in the runtime system.
-  CompareRoot(result, Heap::kTheHoleValueRootIndex);
-  j(equal, miss);
-
-  // If the function does not have an initial map, we're done.
-  Label done;
-  CmpObjectType(result, MAP_TYPE, kScratchRegister);
-  j(not_equal, &done, Label::kNear);
-
-  // Get the prototype from the initial map.
-  movp(result, FieldOperand(result, Map::kPrototypeOffset));
-
-  // All done.
-  bind(&done);
-}
-
-
 void MacroAssembler::SetCounter(StatsCounter* counter, int value) {
   if (FLAG_native_code_counters && counter->Enabled()) {
     Operand counter_operand = ExternalOperand(ExternalReference(counter));