Add separate flag for --trace-stub-failures

src/flag-definitions.h

 // Copyright 2012 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 326 matching lines @@
             true,
             "use random jit cookie to mask large constants")
 
 // codegen.cc
 DEFINE_bool(lazy, true, "use lazy compilation")
 DEFINE_bool(trace_opt, false, "trace lazy optimization")
 DEFINE_bool(trace_opt_stats, false, "trace lazy optimization statistics")
 DEFINE_bool(opt, true, "use adaptive optimizations")
 DEFINE_bool(always_opt, false, "always try to optimize functions")
 DEFINE_bool(prepare_always_opt, false, "prepare for turning on always opt")
-DEFINE_bool(trace_deopt, false, "trace deoptimization")
+DEFINE_bool(trace_deopt, false, "trace optimize function deoptimization")
+DEFINE_bool(trace_stub_failures, false,
+            "trace deoptimization of generated code stubs")
 
 // compiler.cc
 DEFINE_int(min_preparse_length, 1024,
            "minimum length for automatic enable preparsing")
 DEFINE_bool(always_full_compiler, false,
             "try to use the dedicated run-once backend for all code")
 DEFINE_int(max_opt_count, 10,
            "maximum number of optimization attempts before giving up.")
 
 // compilation-cache.cc
@@ skipping 373 matching lines @@
 #undef DEFINE_bool
 #undef DEFINE_int
 #undef DEFINE_string
 #undef DEFINE_implication
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS