Adding supported checks and flags to window.performance.

sdk/lib/html/dart2js/html_dart2js.dart

 library html;
 
 import 'dart:async';
 import 'dart:collection';
 import 'dart:html_common';
 import 'dart:indexed_db';
 import 'dart:isolate';
 import 'dart:json' as json;
 import 'dart:math';
 import 'dart:svg' as svg;
@@ skipping 329 matching lines @@
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.FIREFOX)
 @SupportedBrowser(SupportedBrowser.IE, '10')
 @SupportedBrowser(SupportedBrowser.SAFARI)
 class ArrayBuffer native "*ArrayBuffer" {
 
   ///@docsEditable true
   factory ArrayBuffer(int length) => ArrayBuffer._create(length);
   static ArrayBuffer _create(int length) => JS('ArrayBuffer', 'new ArrayBuffer(#)', length);
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => JS('bool', 'typeof window.ArrayBuffer != "undefined"');
 
   /// @domName ArrayBuffer.byteLength; @docsEditable true
   final int byteLength;
 
   /// @domName ArrayBuffer.slice;
   ArrayBuffer slice(int begin, [int end]) {
     // IE10 supports ArrayBuffers but does not have the slice method.
     if (JS('bool', '!!#.slice', this)) {
       if (?end) {
@@ skipping 1081 matching lines @@
 
 
 /// @domName HTMLContentElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME, '25')
 @Experimental()
 class ContentElement extends Element native "*HTMLContentElement" {
 
   ///@docsEditable true
   factory ContentElement() => document.$dom_createElement("content");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('content');
 
   /// @domName HTMLContentElement.resetStyleInheritance; @docsEditable true
   bool resetStyleInheritance;
 
   /// @domName HTMLContentElement.select; @docsEditable true
   String select;
 
   /// @domName HTMLContentElement.getDistributedNodes; @docsEditable true
   @Returns('NodeList') @Creates('NodeList')
@@ skipping 3809 matching lines @@
 /// @domName HTMLDataListElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.FIREFOX)
 @SupportedBrowser(SupportedBrowser.IE, '10')
 @SupportedBrowser(SupportedBrowser.SAFARI)
 class DataListElement extends Element native "*HTMLDataListElement" {
 
   ///@docsEditable true
   factory DataListElement() => document.$dom_createElement("datalist");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('datalist');
 
   /// @domName HTMLDataListElement.options; @docsEditable true
   final HtmlCollection options;
 }
 // Copyright (c) 2012, 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.
 
 
@@ skipping 206 matching lines @@
 
 /// @domName HTMLDetailsElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.SAFARI)
 @Experimental()
 class DetailsElement extends Element native "*HTMLDetailsElement" {
 
   ///@docsEditable true
   factory DetailsElement() => document.$dom_createElement("details");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('details');
 
   /// @domName HTMLDetailsElement.open; @docsEditable true
   bool open;
 }
 // Copyright (c) 2012, 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.
 
 
@@ skipping 2907 matching lines @@
 
 /// @domName HTMLEmbedElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.IE)
 @SupportedBrowser(SupportedBrowser.SAFARI)
 class EmbedElement extends Element native "*HTMLEmbedElement" {
 
   ///@docsEditable true
   factory EmbedElement() => document.$dom_createElement("embed");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('embed');
 
   /// @domName HTMLEmbedElement.align; @docsEditable true
   String align;
 
   /// @domName HTMLEmbedElement.height; @docsEditable true
   String height;
 
   /// @domName HTMLEmbedElement.name; @docsEditable true
   String name;
@@ skipping 4235 matching lines @@
 
 /// @domName HTMLKeygenElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.SAFARI)
 @Experimental()
 class KeygenElement extends Element native "*HTMLKeygenElement" {
 
   ///@docsEditable true
   factory KeygenElement() => document.$dom_createElement("keygen");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('keygen') && (new Element.tag('keygen') is KeygenElement);
 
   /// @domName HTMLKeygenElement.autofocus; @docsEditable true
   bool autofocus;
 
   /// @domName HTMLKeygenElement.challenge; @docsEditable true
   String challenge;
 
   /// @domName HTMLKeygenElement.disabled; @docsEditable true
   bool disabled;
@@ skipping 198 matching lines @@
   String name;
 }
 // Copyright (c) 2012, 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.
 
 
 /// @domName HTMLMarqueeElement; @docsEditable true
 class MarqueeElement extends Element native "*HTMLMarqueeElement" {
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('marquee')&& (new Element.tag('marquee') is MarqueeElement);
 
   /// @domName HTMLMarqueeElement.behavior; @docsEditable true
   String behavior;
 
   /// @domName HTMLMarqueeElement.bgColor; @docsEditable true
   String bgColor;
 
   /// @domName HTMLMarqueeElement.direction; @docsEditable true
   String direction;
@@ skipping 871 matching lines @@
 
 /// @domName HTMLMeterElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.FIREFOX)
 @SupportedBrowser(SupportedBrowser.SAFARI)
 class MeterElement extends Element native "*HTMLMeterElement" {
 
   ///@docsEditable true
   factory MeterElement() => document.$dom_createElement("meter");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('meter');
 
   /// @domName HTMLMeterElement.high; @docsEditable true
   num high;
 
   /// @domName HTMLMeterElement.labels; @docsEditable true
   @Returns('NodeList') @Creates('NodeList')
   final List<Node> labels;
 
   /// @domName HTMLMeterElement.low; @docsEditable true
@@ skipping 1358 matching lines @@
 
 /// @domName HTMLObjectElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.FIREFOX)
 @SupportedBrowser(SupportedBrowser.SAFARI)
 class ObjectElement extends Element native "*HTMLObjectElement" {
 
   ///@docsEditable true
   factory ObjectElement() => document.$dom_createElement("object");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('object');
 
   /// @domName HTMLObjectElement.code; @docsEditable true
   String code;
 
   /// @domName HTMLObjectElement.data; @docsEditable true
   String data;
 
   /// @domName HTMLObjectElement.form; @docsEditable true
   final FormElement form;
@@ skipping 165 matching lines @@
 
 /// @domName HTMLOutputElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.FIREFOX)
 @SupportedBrowser(SupportedBrowser.SAFARI)
 class OutputElement extends Element native "*HTMLOutputElement" {
 
   ///@docsEditable true
   factory OutputElement() => document.$dom_createElement("output");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('output');
 
   /// @domName HTMLOutputElement.defaultValue; @docsEditable true
   String defaultValue;
 
   /// @domName HTMLOutputElement.form; @docsEditable true
   final FormElement form;
 
   /// @domName HTMLOutputElement.htmlFor; @docsEditable true
   DomSettableTokenList htmlFor;
@@ skipping 107 matching lines @@
 
   /// @domName HTMLParamElement.value; @docsEditable true
   String value;
 }
 // Copyright (c) 2012, 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.
 
 
 /// @domName Performance; @docsEditable true
+@SupportedBrowser(SupportedBrowser.CHROME)
+@SupportedBrowser(SupportedBrowser.FIREFOX)
+@SupportedBrowser(SupportedBrowser.IE)
 class Performance extends EventTarget native "*Performance" {
 
+  /// Checks if this type is supported on the current platform.
+  static bool get supported => JS('bool', '!!(window.performance)');
+
   /// @domName Performance.memory; @docsEditable true
   final MemoryInfo memory;
 
   /// @domName Performance.navigation; @docsEditable true
   final PerformanceNavigation navigation;
 
   /// @domName Performance.timing; @docsEditable true
   final PerformanceTiming timing;
 
   /// @domName Performance.now; @docsEditable true
@@ skipping 199 matching lines @@
 /// @domName HTMLProgressElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.FIREFOX)
 @SupportedBrowser(SupportedBrowser.IE, '10')
 @SupportedBrowser(SupportedBrowser.SAFARI)
 class ProgressElement extends Element native "*HTMLProgressElement" {
 
   ///@docsEditable true
   factory ProgressElement() => document.$dom_createElement("progress");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('progress');
 
   /// @domName HTMLProgressElement.labels; @docsEditable true
   @Returns('NodeList') @Creates('NodeList')
   final List<Node> labels;
 
   /// @domName HTMLProgressElement.max; @docsEditable true
   num max;
 
   /// @domName HTMLProgressElement.position; @docsEditable true
@@ skipping 860 matching lines @@
 // Copyright (c) 2012, 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.
 
 
 /// @domName HTMLShadowElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME, '25')
 @Experimental()
 class ShadowElement extends Element native "*HTMLShadowElement" {
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('shadow');
 
   /// @domName HTMLShadowElement.olderShadowRoot; @docsEditable true
   final ShadowRoot olderShadowRoot;
 
   /// @domName HTMLShadowElement.resetStyleInheritance; @docsEditable true
   bool resetStyleInheritance;
 }
 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
@@ skipping 2240 matching lines @@
 
 /// @domName HTMLTrackElement; @docsEditable true
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.IE, '10')
 @SupportedBrowser(SupportedBrowser.SAFARI)
 class TrackElement extends Element native "*HTMLTrackElement" {
 
   ///@docsEditable true
   factory TrackElement() => document.$dom_createElement("track");
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => Element.isTagSupported('track');
 
   static const int ERROR = 3;
 
   static const int LOADED = 2;
 
   static const int LOADING = 1;
 
   static const int NONE = 0;
 
@@ skipping 2212 matching lines @@
 @SupportedBrowser(SupportedBrowser.CHROME)
 @SupportedBrowser(SupportedBrowser.FIREFOX)
 @SupportedBrowser(SupportedBrowser.IE, '10')
 @SupportedBrowser(SupportedBrowser.SAFARI)
 class WebSocket extends EventTarget native "*WebSocket" {
 
   ///@docsEditable true
   factory WebSocket(String url) => WebSocket._create(url);
   static WebSocket _create(String url) => JS('WebSocket', 'new WebSocket(#)', url);
 
-  /**
-   * Checks if this type is supported on the current platform
-   */
+  /// Checks if this type is supported on the current platform.
   static bool get supported => JS('bool', 'typeof window.WebSocket != "undefined"');
 
   /// @domName EventTarget.addEventListener, EventTarget.removeEventListener, EventTarget.dispatchEvent; @docsEditable true
   WebSocketEvents get on =>
     new WebSocketEvents(this);
 
   static const int CLOSED = 3;
 
   static const int CLOSING = 2;
 
@@ skipping 386 matching lines @@
   /// @domName Window.pageYOffset; @docsEditable true
   final int pageYOffset;
 
   /// @domName Window.parent; @docsEditable true
   WindowBase get parent => _convertNativeToDart_Window(this._parent);
   @JSName('parent')
   @Creates('Window|=Object') @Returns('Window|=Object')
   final dynamic _parent;
 
   /// @domName Window.performance; @docsEditable true
+  @SupportedBrowser(SupportedBrowser.CHROME) @SupportedBrowser(SupportedBrowser.FIREFOX) @SupportedBrowser(SupportedBrowser.IE)
   final Performance performance;
 
   /// @domName Window.personalbar; @docsEditable true
   final BarInfo personalbar;
 
   /// @domName Window.screen; @docsEditable true
   final Screen screen;
 
   /// @domName Window.screenLeft; @docsEditable true
   final int screenLeft;
@@ skipping 5453 matching lines @@
       _position = nextPosition;
       return true;
     }
     _current = null;
     _position = _array.length;
     return false;
   }
 
   T get current => _current;
 }