debugger: take help message from commands

lib/_debugger.js

@@ -307,10 +307,25 @@ Client.prototype.step = function(action, count, cb) {
 };
 
 
+var commands = [
+  'backtrace',
+  'continue',
+  'help',
+  'info breakpoints',
+  'kill',
+  'list',
+  'next',
+  'print',
+  'quit',
+  'run',
+  'scripts',
+  'step',
+  'version',
+];
 
 
-var helpMessage = 'Commands: run, kill, print, step, next, ' +
+var helpMessage = 'Commands: ' + commands.join(', ');
-                  'continue, list, scripts, backtrace, version, quit';
+
 
 function SourceUnderline(sourceText, position) {
   if (!sourceText) return;
@@ -402,23 +417,6 @@ function Interface() {
 }
 
 
-var commands = [
-  'backtrace',
-  'continue',
-  'help',
-  'info breakpoints',
-  'kill',
-  'list',
-  'next',
-  'print',
-  'quit',
-  'run',
-  'scripts',
-  'step',
-  'version',
-];
-
-
 Interface.prototype.complete = function(line) {
   // Match me with a command.
   var matches = [];