First try at removing ? from HTML.

tools/dom/src/chrome/app_runtime.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.runtime
 
 part of chrome;
 
 /**
  * Types
@@ skipping 39 matching lines @@
   /// Callback to be compatible with WebIntents.
   void postFailure() => JS('void', '#.postFailure()', this._jsObject);
 
 }
 
 class AppRuntimeLaunchItem extends ChromeObject {
   /*
    * Public constructor
    */
   AppRuntimeLaunchItem({FileEntry entry, String type}) {
-    if (?entry)
+    if (entry != null)
       this.entry = entry;
-    if (?type)
+    if (type != null)
       this.type = type;
   }
 
   /*
    * Private constructor
    */
   AppRuntimeLaunchItem._proxy(_jsObject) : super._proxy(_jsObject);
 
   /*
    * Public accessors
@@ skipping 12 matching lines @@
     JS('void', '#.type = #', this._jsObject, type);
   }
 
 }
 
 class AppRuntimeLaunchData extends ChromeObject {
   /*
    * Public constructor
    */
   AppRuntimeLaunchData({AppRuntimeIntent intent, String id, List<AppRuntimeLaunchItem> items}) {
-    if (?intent)
+    if (intent != null)
       this.intent = intent;
-    if (?id)
+    if (id != null)
       this.id = id;
-    if (?items)
+    if (items != null)
       this.items = items;
   }
 
   /*
    * Private constructor
    */
   AppRuntimeLaunchData._proxy(_jsObject) : super._proxy(_jsObject);
 
   /*
    * Public accessors
@@ skipping 23 matching lines @@
     JS('void', '#.items = #', this._jsObject, convertArgument(items));
   }
 
 }
 
 class AppRuntimeIntentResponse extends ChromeObject {
   /*
    * Public constructor
    */
   AppRuntimeIntentResponse({int intentId, bool success, Object data}) {
-    if (?intentId)
+    if (intentId != null)
       this.intentId = intentId;
-    if (?success)
+    if (success != null)
       this.success = success;
-    if (?data)
+    if (data != null)
       this.data = data;
   }
 
   /*
    * Private constructor
    */
   AppRuntimeIntentResponse._proxy(_jsObject) : super._proxy(_jsObject);
 
   /*
    * Public accessors
@@ skipping 23 matching lines @@
 
 /**
  * Events
  */
 
 /// Fired when an app is launched from the launcher or in response to a web
 /// intent.
 class Event_app_runtime_onLaunched extends Event {
   void addListener(void callback(AppRuntimeLaunchData launchData)) {
     void __proxy_callback(launchData) {
-      if (?callback) {
+      if (callback != null) {
         callback(new AppRuntimeLaunchData._proxy(launchData));
       }
     }
     super.addListener(callback);
   }
 
   void removeListener(void callback(AppRuntimeLaunchData launchData)) {
     void __proxy_callback(launchData) {
-      if (?callback) {
+      if (callback != null) {
         callback(new AppRuntimeLaunchData._proxy(launchData));
       }
     }
     super.removeListener(callback);
   }
 
   bool hasListener(void callback(AppRuntimeLaunchData launchData)) {
     void __proxy_callback(launchData) {
-      if (?callback) {
+      if (callback != null) {
         callback(new AppRuntimeLaunchData._proxy(launchData));
       }
     }
     super.hasListener(callback);
   }
 
   Event_app_runtime_onLaunched(jsObject) : super._(jsObject, 1);
 }
 
 /// Fired at Chrome startup to apps that were running when Chrome last shut
@@ skipping 30 matching lines @@
   /// postIntentResponse is an internal method to responds to an intent
   /// previously sent to a packaged app. This is identified by intentId, and
   /// should only be invoked at most once per intentId.
   void postIntentResponse(AppRuntimeIntentResponse intentResponse) => JS('void', '#.postIntentResponse(#)', this._jsObject, convertArgument(intentResponse));
 
   API_app_runtime(this._jsObject) {
     onLaunched = new Event_app_runtime_onLaunched(JS('', '#.onLaunched', this._jsObject));
     onRestarted = new Event_app_runtime_onRestarted(JS('', '#.onRestarted', this._jsObject));
   }
 }