[compiler] Remove --ignition-preserve-bytecode 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 281 matching lines @@
 DEFINE_IMPLICATION(ignition_staging, ignition)
 DEFINE_IMPLICATION(ignition_staging, ignition_osr)
 DEFINE_STRING(ignition_filter, "*", "filter for ignition interpreter")
 DEFINE_BOOL(ignition_deadcode, true,
             "use ignition dead code elimination optimizer")
 DEFINE_BOOL(ignition_osr, false, "enable support for OSR from ignition code")
 DEFINE_BOOL(ignition_peephole, true, "use ignition peephole optimizer")
 DEFINE_BOOL(ignition_reo, true, "use ignition register equivalence optimizer")
 DEFINE_BOOL(ignition_filter_expression_positions, true,
             "filter expression positions before the bytecode pipeline")
-DEFINE_BOOL(ignition_preserve_bytecode, true,
-            "preserve generated bytecode even when switching tiers")
 DEFINE_BOOL(print_bytecode, false,
             "print bytecode generated by ignition interpreter")
 DEFINE_BOOL(trace_ignition, false,
             "trace the bytecodes executed by the ignition interpreter")
 DEFINE_BOOL(trace_ignition_codegen, false,
             "trace the codegen of ignition interpreter bytecode handlers")
 DEFINE_BOOL(trace_ignition_dispatches, false,
             "traces the dispatches to bytecode handlers by the ignition "
             "interpreter")
 DEFINE_STRING(trace_ignition_dispatches_output_file, nullptr,
@@ skipping 911 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