[fullcodegen] Avoid arguments juggling when calling a JS runtime function.

src/full-codegen/x64/full-codegen-x64.cc

Index: src/full-codegen/x64/full-codegen-x64.cc
diff --git a/src/full-codegen/x64/full-codegen-x64.cc b/src/full-codegen/x64/full-codegen-x64.cc
index f942f697f7253f331beb68124ff9716ad032725e..d38121760acd4b9e538a56dadc90e0f7f5c9118c 100644
--- a/src/full-codegen/x64/full-codegen-x64.cc
+++ b/src/full-codegen/x64/full-codegen-x64.cc
@@ -3230,11 +3230,13 @@ void FullCodeGenerator::EmitCreateIterResultObject(CallRuntime* expr) {
 
 
 void FullCodeGenerator::EmitLoadJSRuntimeFunction(CallRuntime* expr) {
-  // Push the builtins object as receiver.
+  // Push function.
+  __ LoadNativeContextSlot(expr->context_index(), rax);
+  PushOperand(rax);
+
+  // Push undefined as receiver.
   OperandStackDepthIncrement(1);
   __ PushRoot(Heap::kUndefinedValueRootIndex);
-
-  __ LoadNativeContextSlot(expr->context_index(), rax);
 }
 
 
@@ -3257,13 +3259,8 @@ void FullCodeGenerator::VisitCallRuntime(CallRuntime* expr) {
 
   if (expr->is_jsruntime()) {
     Comment cmnt(masm_, "[ CallRuntime");
-
     EmitLoadJSRuntimeFunction(expr);
 
-    // Push the target function under the receiver.
-    PushOperand(Operand(rsp, 0));
-    __ movp(Operand(rsp, kPointerSize), rax);
-
     // Push the arguments ("left-to-right").
     for (int i = 0; i < arg_count; i++) {
       VisitForStackValue(args->at(i));