Add flag trap_on_stub_deopt. We want to be able to trap on hydrogen stub bailouts.

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index c68beb5ed92931d9c78b1315481b219a68957977..c0ad4a8e17ab2467c9f63dacd75ef21e2d1e5040 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -264,6 +264,8 @@ DEFINE_int(deopt_every_n_garbage_collections,
            "deoptimize every n garbage collections")
 DEFINE_bool(print_deopt_stress, false, "print number of possible deopt points")
 DEFINE_bool(trap_on_deopt, false, "put a break point before deoptimizing")
+DEFINE_bool(trap_on_stub_deopt, false,
+            "put a break point before deoptimizing a stub")
 DEFINE_bool(deoptimize_uncommon_cases, true, "deoptimize uncommon cases")
 DEFINE_bool(polymorphic_inlining, true, "polymorphic inlining")
 DEFINE_bool(use_osr, true, "use on-stack replacement")