Add flag --collect-megamorphic-maps-from-stub-cache to help diagnose a

src/flag-definitions.h

 // Copyright 2011 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 110 matching lines @@
 DEFINE_bool(alloc_lithium, true, "use lithium register allocator")
 DEFINE_bool(use_lithium, true, "use lithium code generator")
 DEFINE_bool(use_range, true, "use hydrogen range analysis")
 DEFINE_bool(eliminate_dead_phis, true, "eliminate dead phis")
 DEFINE_bool(use_gvn, true, "use hydrogen global value numbering")
 DEFINE_bool(use_canonicalizing, true, "use hydrogen instruction canonicalizing")
 DEFINE_bool(use_inlining, true, "use function inlining")
 DEFINE_bool(limit_inlining, true, "limit code size growth from inlining")
 DEFINE_bool(eliminate_empty_blocks, true, "eliminate empty blocks")
 DEFINE_bool(loop_invariant_code_motion, true, "loop invariant code motion")
+DEFINE_bool(collect_megamorphic_maps_from_stub_cache,
+            true,
+            "crankshaft harvests type feedback from stub cache")
 DEFINE_bool(hydrogen_stats, false, "print statistics for hydrogen")
 DEFINE_bool(trace_hydrogen, false, "trace generated hydrogen to file")
 DEFINE_bool(trace_inlining, false, "trace inlining decisions")
 DEFINE_bool(trace_alloc, false, "trace register allocator")
 DEFINE_bool(trace_all_uses, false, "trace all use positions")
 DEFINE_bool(trace_range, false, "trace range analysis")
 DEFINE_bool(trace_gvn, false, "trace global value numbering")
 DEFINE_bool(trace_representation, false, "trace representation types")
 DEFINE_bool(stress_pointer_maps, false, "pointer map for every instruction")
 DEFINE_bool(stress_environments, false, "environment for every instruction")
@@ skipping 405 matching lines @@
 #undef FLAG
 
 #undef DEFINE_bool
 #undef DEFINE_int
 #undef DEFINE_string
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META