Improve the UseCounters for HTMLInputElement.webkitdirectory and .incremental

Source/core/html/HTMLInputElement.idl

Index: Source/core/html/HTMLInputElement.idl
diff --git a/Source/core/html/HTMLInputElement.idl b/Source/core/html/HTMLInputElement.idl
index a26fe72b1449391670c27ea2d02d759283743f30..209b1773c50d1552f3ede9ab965f71c4c96ca396 100644
--- a/Source/core/html/HTMLInputElement.idl
+++ b/Source/core/html/HTMLInputElement.idl
@@ -93,8 +93,8 @@ interface HTMLInputElement : HTMLElement {
                            optional DOMString direction);
 
     // Non-standard attributes
-    [Reflect] attribute boolean webkitdirectory;
-    [Reflect] attribute boolean incremental;
+    [Reflect, MeasureAs=PrefixedDirectoryAttribute] attribute boolean webkitdirectory;
+    [Reflect, MeasureAs=IncrementalAttribute] attribute boolean incremental;
 
     // See http://www.w3.org/TR/html-media-capture/
     [Conditional=MEDIA_CAPTURE, Reflect] attribute boolean capture;