Faster invocation of custom comparator function.

src/x64/virtual-frame-x64.h

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 300 matching lines @@
   // argument is given as a result which does not have to be eax or
   // even a register.  The argument is consumed by the call.
   Result CallStub(CodeStub* stub, Result* arg);
 
   // Call stub that takes a pair of arguments passed in edx (arg0, rdx) and
   // eax (arg1, rax).  The arguments are given as results which do not have
   // to be in the proper registers or even in registers.  The
   // arguments are consumed by the call.
   Result CallStub(CodeStub* stub, Result* arg0, Result* arg1);
 
+  // Call JS function from top of the stack with arguments
+  // taken from the stack.
+  Result CallJSFunction(int arg_count);
+
   // Call runtime given the number of arguments expected on (and
   // removed from) the stack.
   Result CallRuntime(Runtime::Function* f, int arg_count);
   Result CallRuntime(Runtime::FunctionId id, int arg_count);
 
 #ifdef ENABLE_DEBUGGER_SUPPORT
   void DebugBreak();
 #endif
 
   // Invoke builtin given the number of arguments it expects on (and
@@ skipping 233 matching lines @@
 
   // Classes that need raw access to the elements_ array.
   friend class DeferredCode;
   friend class JumpTarget;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_VIRTUAL_FRAME_X64_H_