Adding support checks for FileSystem APIs and making APIs not webkit-specific.

sdk/lib/html/dart2js/html_dart2js.dart

Index: sdk/lib/html/dart2js/html_dart2js.dart
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 2a525136f049e5697bf5105e4fd405cce3036139..9bdcadbd476e740c062460d9d5770f90b6b98d70 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -9345,6 +9345,11 @@ class FileReaderSync native "*FileReaderSync" {
 /// @domName DOMFileSystem; @docsEditable true
 class FileSystem native "*DOMFileSystem" {
 
+  /**
+   * Checks if this type is supported on the current platform
+   */
+  static bool get supported => JS('bool', '!!(window.webkitRequestFileSystem)');
+
   /// @domName DOMFileSystem.name; @docsEditable true
   final String name;
 
@@ -21717,11 +21722,14 @@ class Window extends EventTarget implements WindowBase native "@*DOMWindow" {
   Point webkitConvertPointFromPageToNode(Node node, Point p) native;
 
   /// @domName DOMWindow.webkitRequestFileSystem; @docsEditable true
-  void webkitRequestFileSystem(int type, int size, FileSystemCallback successCallback, [ErrorCallback errorCallback]) native;
+  @JSName('webkitRequestFileSystem')
+  @SupportedBrowser(SupportedBrowser.CHROME) @Experimental()
+  void requestFileSystem(int type, int size, FileSystemCallback successCallback, [ErrorCallback errorCallback]) native;
 
   /// @domName DOMWindow.webkitResolveLocalFileSystemURL; @docsEditable true
   @JSName('webkitResolveLocalFileSystemURL')
-  void webkitResolveLocalFileSystemUrl(String url, EntryCallback successCallback, [ErrorCallback errorCallback]) native;
+  @SupportedBrowser(SupportedBrowser.CHROME) @Experimental()
+  void resolveLocalFileSystemUrl(String url, EntryCallback successCallback, [ErrorCallback errorCallback]) native;
 
 }
 
@@ -22061,18 +22069,24 @@ class WorkerContext extends EventTarget native "*WorkerContext" {
   int setTimeout(TimeoutHandler handler, int timeout) native;
 
   /// @domName WorkerContext.webkitRequestFileSystem; @docsEditable true
-  void webkitRequestFileSystem(int type, int size, [FileSystemCallback successCallback, ErrorCallback errorCallback]) native;
+  @JSName('webkitRequestFileSystem')
+  @SupportedBrowser(SupportedBrowser.CHROME) @Experimental()
+  void requestFileSystem(int type, int size, [FileSystemCallback successCallback, ErrorCallback errorCallback]) native;
 
   /// @domName WorkerContext.webkitRequestFileSystemSync; @docsEditable true
-  FileSystemSync webkitRequestFileSystemSync(int type, int size) native;
+  @JSName('webkitRequestFileSystemSync')
+  @SupportedBrowser(SupportedBrowser.CHROME) @Experimental()
+  FileSystemSync requestFileSystemSync(int type, int size) native;
 
   /// @domName WorkerContext.webkitResolveLocalFileSystemSyncURL; @docsEditable true
   @JSName('webkitResolveLocalFileSystemSyncURL')
-  EntrySync webkitResolveLocalFileSystemSyncUrl(String url) native;
+  @SupportedBrowser(SupportedBrowser.CHROME) @Experimental()
+  EntrySync resolveLocalFileSystemSyncUrl(String url) native;
 
   /// @domName WorkerContext.webkitResolveLocalFileSystemURL; @docsEditable true
   @JSName('webkitResolveLocalFileSystemURL')
-  void webkitResolveLocalFileSystemUrl(String url, EntryCallback successCallback, [ErrorCallback errorCallback]) native;
+  @SupportedBrowser(SupportedBrowser.CHROME) @Experimental()
+  void resolveLocalFileSystemUrl(String url, EntryCallback successCallback, [ErrorCallback errorCallback]) native;
 
 
   /**