[flags] adding --trace_for_in_enumerate

src/flag-definitions.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This file defines all of the flags.  It is separated into different section,
 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
 //
 // This include does not have a guard, because it is a template-style include,
 // which can be included multiple times in different modes.  It expects to have
@@ skipping 758 matching lines @@
 // objects.cc
 DEFINE_BOOL(trace_weak_arrays, false, "Trace WeakFixedArray usage")
 DEFINE_BOOL(track_prototype_users, false,
             "Keep track of which maps refer to a given prototype object")
 DEFINE_BOOL(trace_prototype_users, false,
             "Trace updates to prototype user tracking")
 DEFINE_BOOL(eliminate_prototype_chain_checks, true,
             "Collapse prototype chain checks into single-cell checks")
 DEFINE_IMPLICATION(eliminate_prototype_chain_checks, track_prototype_users)
 DEFINE_BOOL(use_verbose_printer, true, "allows verbose printing")
+DEFINE_BOOL(trace_for_in_enumerate, false, "Trace for-in enumerate slow-paths")
 #if TRACE_MAPS
 DEFINE_BOOL(trace_maps, false, "trace map creation")
 #endif
 
 // parser.cc
 DEFINE_BOOL(allow_natives_syntax, false, "allow natives syntax")
 DEFINE_BOOL(trace_parse, false, "trace parsing and preparsing")
 
 // simulator-arm.cc, simulator-arm64.cc and simulator-mips.cc
 DEFINE_BOOL(trace_sim, false, "Trace simulator execution")
@@ skipping 376 matching lines @@
 #undef DEFINE_ALIAS_FLOAT
 #undef DEFINE_ALIAS_ARGS
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA