Eliminate map checks of constant values.

src/flag-definitions.h

Index: src/flag-definitions.h
diff --git a/src/flag-definitions.h b/src/flag-definitions.h
index 63cf66313c642dbc5d9c621266657eae2b57cb1b..85e824901fc68a75a5d4bf68f0a6b53689344248 100644
--- a/src/flag-definitions.h
+++ b/src/flag-definitions.h
@@ -307,6 +307,9 @@ DEFINE_int(parallel_recompilation_delay, 0,
 DEFINE_bool(omit_prototype_checks_for_leaf_maps, true,
             "do not emit prototype checks if all prototypes have leaf maps, "
             "deoptimize the optimized code if the layout of the maps changes.")
+DEFINE_bool(omit_check_maps_for_leaf_maps, true,
+            "do not emit check maps for constant values that have a leaf map, "
+            "deoptimize the optimized code if the layout of the maps changes.")
 
 // Experimental profiler changes.
 DEFINE_bool(experimental_profiler, true, "enable all profiler experiments")