Observatory UI tweaks.

runtime/observatory/lib/src/elements/debugger.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library debugger_page_element;
 
 import 'dart:async';
 import 'dart:html';
 import 'observatory_element.dart';
 import 'package:observatory/app.dart';
@@ skipping 92 matching lines @@
       '\n'
       'Syntax: help            - Show a list of all commands\n'
       '        help <command>  - Help for a specific command\n';
 }
 
 class PrintCommand extends DebuggerCommand {
   PrintCommand(Debugger debugger) : super(debugger, 'print', []) {
     alias = 'p';
   }
 
-  Future run(List<String> args) {
+  Future run(List<String> args) async {
     if (args.length < 1) {
       debugger.console.print('print expects arguments');
-      return new Future.value(null);
+      return;
     }
-    var expr = args.join('');
-    return debugger.isolate.evalFrame(debugger.currentFrame, expr)
-      .then((ServiceObject response) {
-        if (response is DartError) {
-          debugger.console.print(response.message);
-        } else {
-          debugger.console.print('= ', newline:false);
-          debugger.console.printRef(response);
-        }
-      });
+    if (debugger.currentFrame == null) {
+      debugger.console.print('No stack');
+      return;
+    }
+    var expression = args.join('');
+    var response = await debugger.isolate.evalFrame(debugger.currentFrame,
+                                                    expression);
+    if (response is DartError) {
+      debugger.console.print(response.message);
+    } else {
+      debugger.console.print('= ', newline:false);
+      debugger.console.printRef(response);
+    }
   }
 
   String helpShort = 'Evaluate and print an expression in the current frame';
 
   String helpLong =
       'Evaluate and print an expression in the current frame.\n'
       '\n'
       'Syntax: print <expression>\n'
       '        p <expression>\n';
 }
@@ skipping 170 matching lines @@
       'in the current function';
 
   String helpLong =
       'Continue running the isolate until it reaches the next source location '
       'in the current function.\n'
       '\n'
       'Syntax: next\n';
 }
 
 class StepCommand extends DebuggerCommand {
-  StepCommand(Debugger debugger) : super(debugger, 'step', []);
+  StepCommand(Debugger debugger) : super(debugger, 'step', []) {
+    alias = 's';
+  }
 
   Future run(List<String> args) {
     if (debugger.isolatePaused()) {
       var event = debugger.isolate.pauseEvent;
       if (event.kind == ServiceEvent.kPauseStart) {
         debugger.console.print("Type 'continue' to start the isolate");
         return new Future.value(null);
       }
       if (event.kind == ServiceEvent.kPauseExit) {
         debugger.console.print("Type 'continue' to exit the isolate");
@@ skipping 843 matching lines @@
   Future<String> complete(String line) {
     return cmd.completeCommand(line).then((completions) {
       if (completions.length == 0) {
         // No completions.  Leave the line alone.
         return line;
       } else if (completions.length == 1) {
         // Unambiguous completion.
         return completions[0];
       } else {
         // Ambigous completion.
-        completions = completions.map((s )=> s.trimRight()).toList();
+        completions = completions.map((s) => s.trimRight()).toList();
         console.printBold(completions.toString());
         return _foldCompletions(completions);
       }
     });
   }
 
   // TODO(turnidge): Implement real command line history.
   String lastCommand;
 
   Future run(String command) {
@@ skipping 522 matching lines @@
       });
   }
 
   void focus() {
     $['textBox'].focus();
   }
 
   DebuggerInputElement.created() : super.created();
 }