KeyedLoadIC should have same register spec as LoadIC.

src/x64/code-stubs-x64.cc

Index: src/x64/code-stubs-x64.cc
diff --git a/src/x64/code-stubs-x64.cc b/src/x64/code-stubs-x64.cc
index e8ff2446c66afdb73039c2e2ece4852f7b610766..3372cc2f1e8d5b337b0ee1848adf9c8a7463bf6c 100644
--- a/src/x64/code-stubs-x64.cc
+++ b/src/x64/code-stubs-x64.cc
@@ -780,24 +780,15 @@ void MathPowStub::Generate(MacroAssembler* masm) {
 
 void FunctionPrototypeStub::Generate(MacroAssembler* masm) {
   Label miss;
-  Register receiver;
+  Register receiver = LoadIC::ReceiverRegister();
+  Register name = LoadIC::NameRegister();
+
+  ASSERT(kind() == Code::LOAD_IC ||
+         kind() == Code::KEYED_LOAD_IC);
+
   if (kind() == Code::KEYED_LOAD_IC) {
-    // ----------- S t a t e -------------
-    //  -- rax    : key
-    //  -- rdx    : receiver
-    //  -- rsp[0] : return address
-    // -----------------------------------
-    __ Cmp(rax, isolate()->factory()->prototype_string());
+    __ Cmp(name, isolate()->factory()->prototype_string());
     __ j(not_equal, &miss);
-    receiver = rdx;
-  } else {
-    ASSERT(kind() == Code::LOAD_IC);
-    // ----------- S t a t e -------------
-    //  -- rax    : receiver
-    //  -- rcx    : name
-    //  -- rsp[0] : return address
-    // -----------------------------------
-    receiver = rax;
   }
 
   StubCompiler::GenerateLoadFunctionPrototype(masm, receiver, r8, r9, &miss);