[debugger] do not enable liveedit by default.

And a drive-by clean up of unused flag.

R=jgruber@chromium.org
BUG=v8:5530

Review-Url: https://codereview.chromium.org/2744553002
Cr-Commit-Position: refs/heads/master@{#43692}

src/d8.cc

@@ -2030,6 +2030,8 @@ class InspectorClient : public v8_inspector::V8InspectorClient {
             .ToLocalChecked();
     CHECK(context->Global()->Set(context, function_name, function).FromJust());
 
+    v8::debug::SetLiveEditEnabled(isolate_, true);
+
     context_.Reset(isolate_, context);
   }
 

src/debug/debug-interface.h

@@ -61,7 +61,7 @@ MaybeLocal<Value> Call(Local<Context> context, v8::Local<v8::Function> fun,
  * (default Isolate if not provided). V8 will abort if LiveEdit is
  * unexpectedly used. LiveEdit is enabled by default.
  */
-void SetLiveEditEnabled(Isolate* isolate, bool enable);
+V8_EXPORT_PRIVATE void SetLiveEditEnabled(Isolate* isolate, bool enable);
 
 // Schedule a debugger break to happen when JavaScript code is run
 // in the given isolate.

src/debug/debug.cc

@@ -42,7 +42,7 @@ Debug::Debug(Isolate* isolate)
       is_active_(false),
       hook_on_function_call_(false),
       is_suppressed_(false),
-      live_edit_enabled_(true),  // TODO(yangguo): set to false by default.
+      live_edit_enabled_(false),
       break_disabled_(false),
       break_points_active_(true),
       break_on_exception_(false),

src/flag-definitions.h

@@ -849,7 +849,6 @@ DEFINE_IMPLICATION(trace_array_abuse, trace_js_array_abuse)
 DEFINE_IMPLICATION(trace_array_abuse, trace_external_array_abuse)
 
 // debugger
-DEFINE_BOOL(trace_debug_json, false, "trace debugging JSON request/response")
 DEFINE_BOOL(enable_liveedit, true, "enable liveedit experimental feature")
 DEFINE_BOOL(
     trace_side_effect_free_debug_evaluate, false,