First try at removing ? from HTML.

tools/dom/src/chrome/app_window.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.
 
 // Generated from namespace: app.window
 
 part of chrome;
 
 /**
  * Types
  */
 
 class AppWindowCreateWindowOptions extends ChromeObject {
   /*
    * Public constructor
    */
   AppWindowCreateWindowOptions({String id, int defaultWidth, int defaultHeight, int defaultLeft, int defaultTop, int width, int height, int left, int top, int minWidth, int minHeight, int maxWidth, int maxHeight, String type, String frame, AppWindowBounds bounds, bool transparentBackground, bool hidden, bool singleton}) {
-    if (?id)
+    if (id != null)
       this.id = id;
-    if (?defaultWidth)
+    if (defaultWidth != null)
       this.defaultWidth = defaultWidth;
-    if (?defaultHeight)
+    if (defaultHeight != null)
       this.defaultHeight = defaultHeight;
-    if (?defaultLeft)
+    if (defaultLeft != null)
       this.defaultLeft = defaultLeft;
-    if (?defaultTop)
+    if (defaultTop != null)
       this.defaultTop = defaultTop;
-    if (?width)
+    if (width != null)
       this.width = width;
-    if (?height)
+    if (height != null)
       this.height = height;
-    if (?left)
+    if (left != null)
       this.left = left;
-    if (?top)
+    if (top != null)
       this.top = top;
-    if (?minWidth)
+    if (minWidth != null)
       this.minWidth = minWidth;
-    if (?minHeight)
+    if (minHeight != null)
       this.minHeight = minHeight;
-    if (?maxWidth)
+    if (maxWidth != null)
       this.maxWidth = maxWidth;
-    if (?maxHeight)
+    if (maxHeight != null)
       this.maxHeight = maxHeight;
-    if (?type)
+    if (type != null)
       this.type = type;
-    if (?frame)
+    if (frame != null)
       this.frame = frame;
-    if (?bounds)
+    if (bounds != null)
       this.bounds = bounds;
-    if (?transparentBackground)
+    if (transparentBackground != null)
       this.transparentBackground = transparentBackground;
-    if (?hidden)
+    if (hidden != null)
       this.hidden = hidden;
-    if (?singleton)
+    if (singleton != null)
       this.singleton = singleton;
   }
 
   /*
    * Private constructor
    */
   AppWindowCreateWindowOptions._proxy(_jsObject) : super._proxy(_jsObject);
 
   /*
    * Public accessors
@@ skipping 146 matching lines @@
     JS('void', '#.singleton = #', this._jsObject, singleton);
   }
 
 }
 
 class AppWindowBounds extends ChromeObject {
   /*
    * Public constructor
    */
   AppWindowBounds({int left, int top, int width, int height}) {
-    if (?left)
+    if (left != null)
       this.left = left;
-    if (?top)
+    if (top != null)
       this.top = top;
-    if (?width)
+    if (width != null)
       this.width = width;
-    if (?height)
+    if (height != null)
       this.height = height;
   }
 
   /*
    * Private constructor
    */
   AppWindowBounds._proxy(_jsObject) : super._proxy(_jsObject);
 
   /*
    * Public accessors
@@ skipping 207 matching lines @@
   /// that takes effect.
   // 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.
 
   // TODO(sashab): This override is no longer needed once prefixes are removed.
   void create(String url,
               [AppWindowCreateWindowOptions options,
               void callback(AppWindowAppWindow created_window)]) {
     void __proxy_callback(created_window) {
-      if (?callback)
+      if (callback != null)
         callback(new AppWindowAppWindow._proxy(created_window));
     }
     JS('void', '#.create(#, #, #)', this._jsObject, url, convertArgument(options),
        convertDartClosureToJS(__proxy_callback, 1));
   }
 
   /// Returns an $ref:AppWindow object for the current script context (ie
   /// JavaScript 'window' object). This can also be called on a handle to a
   /// script context for another page, for example:
   /// otherWindow.chrome.app.window.current().
   // 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.
 
   // TODO(sashab, kalman): Fix IDL parser to read function return values
   // correctly. Currently, it just reads void for all functions.
   AppWindowAppWindow current() =>
       new AppWindowAppWindow._proxy(JS('void', '#.current()', this._jsObject));
 
   void initializeAppWindow(Object state) => JS('void', '#.initializeAppWindow(#)', this._jsObject, convertArgument(state));
 
   API_app_window(this._jsObject) {
     onBoundsChanged = new Event_app_window_onBoundsChanged(JS('', '#.onBoundsChanged', this._jsObject));
     onClosed = new Event_app_window_onClosed(JS('', '#.onClosed', this._jsObject));
     onMaximized = new Event_app_window_onMaximized(JS('', '#.onMaximized', this._jsObject));
     onMinimized = new Event_app_window_onMinimized(JS('', '#.onMinimized', this._jsObject));
     onRestored = new Event_app_window_onRestored(JS('', '#.onRestored', this._jsObject));
   }
 }