Removing redundant stub for runtime native calls.

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
===================================================================
--- src/x64/macro-assembler-x64.cc	(revision 3744)
+++ src/x64/macro-assembler-x64.cc	(working copy)
@@ -344,10 +344,14 @@
     return;
   }
 
-  Runtime::FunctionId function_id =
-      static_cast<Runtime::FunctionId>(f->stub_id);
-  RuntimeStub stub(function_id, num_arguments);
-  CallStub(&stub);
+  // TODO(1236192): Most runtime routines don't need the number of
+  // arguments passed in because it is constant. At some point we
+  // should remove this need and make the runtime routine entry code
+  // smarter.
+  movq(rax, Immediate(num_arguments));
+  movq(rbx, ExternalReference(f));
+  CEntryStub ces(f->result_size);
+  CallStub(&ces);
 }