[debugger] debug-evaluate should not not modify local values.

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 579 matching lines @@
 
 // compilation-cache.cc
 DEFINE_BOOL(compilation_cache, true, "enable compilation cache")
 
 DEFINE_BOOL(cache_prototype_transitions, true, "cache prototype transitions")
 
 // cpu-profiler.cc
 DEFINE_INT(cpu_profiler_sampling_interval, 1000,
            "CPU profiler sampling interval in microseconds")
 
-// debug.cc
-DEFINE_BOOL(trace_debug_json, false, "trace debugging JSON request/response")
+// Array abuse tracing
 DEFINE_BOOL(trace_js_array_abuse, false,
             "trace out-of-bounds accesses to JS arrays")
 DEFINE_BOOL(trace_external_array_abuse, false,
             "trace out-of-bounds-accesses to external arrays")
 DEFINE_BOOL(trace_array_abuse, false,
             "trace out-of-bounds accesses to all arrays")
 DEFINE_IMPLICATION(trace_array_abuse, trace_js_array_abuse)
 DEFINE_IMPLICATION(trace_array_abuse, trace_external_array_abuse)
+
+// debugger
+DEFINE_BOOL(debug_eval_readonly_locals, true,
+            "do not update locals after debug-evaluate")
+DEFINE_BOOL(trace_debug_json, false, "trace debugging JSON request/response")
 DEFINE_BOOL(enable_liveedit, true, "enable liveedit experimental feature")
 DEFINE_BOOL(hard_abort, true, "abort by crashing")
 
 // execution.cc
 DEFINE_INT(stack_size, V8_DEFAULT_STACK_SIZE_KB,
            "default size of stack region v8 is allowed to use (in kBytes)")
 
 // frames.cc
 DEFINE_INT(max_stack_trace_source_length, 300,
            "maximum length of function source code printed in a stack trace.")
@@ skipping 509 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