Add breakpoints and single-stepping to Observatory.

runtime/bin/vmservice/client/lib/src/elements/script_inset.dart

 // Copyright (c) 2013, 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 script_inset_element;
 
 import 'dart:html';
 import 'observatory_element.dart';
 import 'package:observatory/service.dart';
 import 'package:polymer/polymer.dart';
 
 /// Box with script source code in it.
 @CustomTag('script-inset')
 class ScriptInsetElement extends ObservatoryElement {
   @published Script script;
 
   /// Set the height to make the script inset scroll.  Otherwise it
   /// will show from startPos to endPos.
   @published String height = null;
 
   @published int currentPos;
   @published int startPos;
   @published int endPos;
 
   @observable int currentLine;
   @observable int startLine;
   @observable int endLine;
+  @observable bool linesReady = false;
 
   @observable List<ScriptLine> lines = toObservable([]);
 
   String makeLineId(int line) {
     return 'line-$line';
   }
 
   MutationObserver _observer;
 
-  void _onMutation(mutations, observer) {
+  void _scrollToCurrentPos() {
     var line = shadowRoot.querySelector('#line-$currentLine');
     if (line != null) {
       line.scrollIntoView();
     }
+  }
+
+  void _onMutation(mutations, observer) {
+    _scrollToCurrentPos();
   } 
 
   void attached() {
     super.attached();
     var table = shadowRoot.querySelector('.sourceTable');
     if (table != null) {
       _observer = new MutationObserver(_onMutation);
       _observer.observe(table, childList:true);
     }
   }
 
   void detached() {
     if (_observer != null) {
       _observer.disconnect();
       _observer = null;
     }
     super.detached();
   }
 
   void currentPosChanged(oldValue) {
     _updateLines();
+    _scrollToCurrentPos();
   }
 
   void startPosChanged(oldValue) {
     _updateLines();
   }
 
   void endPosChanged(oldValue) {
     _updateLines();
   }
 
   void scriptChanged(oldValue) {
     _updateLines();
   }
 
   var _updateFuture;
 
   void _updateLines() {
+    linesReady = false;
     if (_updateFuture != null) {
       // Already scheduled.
       return;
     }
     if (script == null) {
       // Wait for script to be assigned.
       return;
     }
     if (!script.loaded) {
       _updateFuture = script.load().then((_) {
         if (script.loaded) {
           _updateFuture = null;
           _updateLines();
         }
       });
       return;
     }
     startLine = (startPos != null
                  ? script.tokenToLine(startPos)
                  : 1);
     currentLine = (currentPos != null
                    ? script.tokenToLine(currentPos)
                    : null);
     endLine = (endPos != null
                ? script.tokenToLine(endPos)
                : script.lines.length);
+
     lines.clear();
     for (int i = (startLine - 1); i <= (endLine - 1); i++) {
       lines.add(script.lines[i]);
     }
+    linesReady = true;
   }
 
   ScriptInsetElement.created() : super.created();
 }
+
+@CustomTag('breakpoint-toggle')
+class BreakpointToggleElement extends ObservatoryElement {
+  @published ScriptLine line;
+  @observable bool busy = false;
+
+  void toggleBreakpoint(var a, var b, var c) {
+    if (busy) {
+      return;
+    }
+    busy = true;
+    if (line.bpt == null) {
+      // No breakpoint.  Set it.
+      line.script.isolate.setBreakpoint(line.script, line.line).then((_) {
+          busy = false;
+      });
+    } else {
+      // Existing breakpoint.  Remove it.
+      line.script.isolate.clearBreakpoint(line.bpt).then((_) {
+          busy = false;
+      });
+    }
+  }
+
+  BreakpointToggleElement.created() : super.created();
+}