Move function prototype handling into a special handler rather than IC

src/x64/lithium-codegen-x64.cc

Index: src/x64/lithium-codegen-x64.cc
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 18b230539b1afc193841f3c9fdb588b77f6d6352..7bc61c8d6493132fffad41a40b28bb081113a198 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -3018,16 +3018,6 @@ void LCodeGen::DoLoadFunctionPrototype(LLoadFunctionPrototype* instr) {
   Register function = ToRegister(instr->function());
   Register result = ToRegister(instr->result());
 
-  // Check that the function really is a function.
-  __ CmpObjectType(function, JS_FUNCTION_TYPE, result);
-  DeoptimizeIf(not_equal, instr->environment());
-
-  // Check whether the function has an instance prototype.
-  Label non_instance;
-  __ testb(FieldOperand(result, Map::kBitFieldOffset),
-           Immediate(1 << Map::kHasNonInstancePrototype));
-  __ j(not_zero, &non_instance, Label::kNear);
-
   // Get the prototype or initial map from the function.
   __ movp(result,
          FieldOperand(function, JSFunction::kPrototypeOrInitialMapOffset));
@@ -3043,12 +3033,6 @@ void LCodeGen::DoLoadFunctionPrototype(LLoadFunctionPrototype* instr) {
 
   // Get the prototype from the initial map.
   __ movp(result, FieldOperand(result, Map::kPrototypeOffset));
-  __ jmp(&done, Label::kNear);
-
-  // Non-instance prototype: Fetch prototype from constructor field
-  // in the function's map.
-  __ bind(&non_instance);
-  __ movp(result, FieldOperand(result, Map::kConstructorOffset));
 
   // All done.
   __ bind(&done);