[turbofan] Better and more sane support for tail calls

src/runtime/runtime-function.cc

Index: src/runtime/runtime-function.cc
diff --git a/src/runtime/runtime-function.cc b/src/runtime/runtime-function.cc
index 16e6149e7c8770411aa870b02fb2c1f562832a26..c17ea6e29849b0c5cb24e520718cbf598ae7f40a 100644
--- a/src/runtime/runtime-function.cc
+++ b/src/runtime/runtime-function.cc
@@ -528,6 +528,12 @@ RUNTIME_FUNCTION(Runtime_Call) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_TailCall) {
+  UNREACHABLE();

[Jarin, 2015/11/12 13:45:12]

Why do not we just do the same thing as Runtime_Call here? Ultimately, we would
want to fuzz this.

[danno, 2015/11/13 10:04:17]

Done.

+  return 0;
+}
+
+
 RUNTIME_FUNCTION(Runtime_Apply) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 5);