[heap] Add --stress-incremental-marking flag.

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 721 matching lines @@
             "Flush code caches in maps during mark compact cycle.")
 DEFINE_BOOL(use_marking_progress_bar, true,
             "Use a progress bar to scan large objects in increments when "
             "incremental marking is active.")
 DEFINE_BOOL(force_marking_deque_overflows, false,
             "force overflows of marking deque by reducing it's size "
             "to 64 words")
 DEFINE_BOOL(stress_compaction, false,
             "stress the GC compactor to flush out bugs (implies "
             "--force_marking_deque_overflows)")
+DEFINE_BOOL(stress_incremental_marking, V8_CONCURRENT_MARKING_BOOL,
+            "force incremental marking for small heaps and run it more often")
 DEFINE_BOOL(manual_evacuation_candidates_selection, false,
             "Test mode only flag. It allows an unit test to select evacuation "
             "candidates pages (requires --stress_compaction).")
 DEFINE_BOOL(fast_promotion_new_space, false,
             "fast promote new space on high survival rates")
 
 // assembler-ia32.cc / assembler-arm.cc / assembler-x64.cc
 DEFINE_BOOL(debug_code, DEBUG_BOOL,
             "generate extra code (assertions) for debugging")
 DEFINE_BOOL(code_comments, false, "emit comments in code disassembly")
@@ skipping 614 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