Describe LiveEdit changes and support preview mode

src/debug-debugger.js

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2052 matching lines @@
 
 
 DebugCommandProcessor.prototype.changeLiveRequest_ = function(request, response) {
   if (!Debug.LiveEdit) {
     return response.failed('LiveEdit feature is not supported');
   }
   if (!request.arguments) {
     return response.failed('Missing arguments');
   }
   var script_id = request.arguments.script_id;
+  var preview_only = !!request.arguments.preview_only;
   
   var scripts = %DebugGetLoadedScripts();
 
   var the_script = null;
   for (var i = 0; i < scripts.length; i++) {
     if (scripts[i].id == script_id) {
       the_script = scripts[i];
     }
   }
   if (!the_script) {
     response.failed('Script not found');
     return;
   }
 
   var change_log = new Array();
   
   if (!IS_STRING(request.arguments.new_source)) {
     throw "new_source argument expected";
   }
 
   var new_source = request.arguments.new_source;
   
-  try {
-    Debug.LiveEdit.SetScriptSource(the_script, new_source, change_log);
-  } catch (e) {
-    if (e instanceof Debug.LiveEdit.Failure) {
-      // Let's treat it as a "success" so that body with change_log will be
-      // sent back. "change_log" will have "failure" field set.
-      change_log.push( { failure: true, message: e.toString() } ); 
-    } else {
-      throw e;
-    }
-  }
-  response.body = {change_log: change_log};
+  var result_description = Debug.LiveEdit.SetScriptSource(the_script,
+      new_source, preview_only, change_log);
+  response.body = {change_log: change_log, result: result_description};
 };
 
 
 // Check whether the previously processed command caused the VM to become
 // running.
 DebugCommandProcessor.prototype.isRunning = function() {
   return this.running_;
 }
 
 
@@ skipping 109 matching lines @@
     case 'string':
     case 'number':
       json = value;
       break
 
     default:
       json = null;
   }
   return json;
 }