Add the HTMLIFrameElement.allowFullscreen reflected attribute

LayoutTests/fast/dom/boolean-attribute-reflection-expected.txt

Index: LayoutTests/fast/dom/boolean-attribute-reflection-expected.txt
diff --git a/LayoutTests/fast/dom/boolean-attribute-reflection-expected.txt b/LayoutTests/fast/dom/boolean-attribute-reflection-expected.txt
index c50eb6f2dfb4c46e122af9f6e3f05a7e6dc80292..c1dd79355a285f513411993c944d2315af5064ad 100644
--- a/LayoutTests/fast/dom/boolean-attribute-reflection-expected.txt
+++ b/LayoutTests/fast/dom/boolean-attribute-reflection-expected.txt
@@ -27,6 +27,10 @@ PASS e = make('hr'); e.removeAttribute('noshade'); e.noShade is false
 PASS e = make('hr'); e.setAttribute('noshade', ''); e.noShade is true
 PASS e = make('hr'); e.setAttribute('noshade', 'x'); e.noShade = false; e.getAttribute('noshade') is null
 PASS e = make('hr'); e.setAttribute('noshade', 'x'); e.noShade = true; e.getAttribute('noshade') is ''
+PASS e = make('iframe'); e.removeAttribute('allowfullscreen'); e.allowFullscreen is false
+PASS e = make('iframe'); e.setAttribute('allowfullscreen', ''); e.allowFullscreen is true
+PASS e = make('iframe'); e.setAttribute('allowfullscreen', 'x'); e.allowFullscreen = false; e.getAttribute('allowfullscreen') is null
+PASS e = make('iframe'); e.setAttribute('allowfullscreen', 'x'); e.allowFullscreen = true; e.getAttribute('allowfullscreen') is ''
 PASS e = make('img'); e.removeAttribute('ismap'); e.isMap is false
 PASS e = make('img'); e.setAttribute('ismap', ''); e.isMap is true
 PASS e = make('img'); e.setAttribute('ismap', 'x'); e.isMap = false; e.getAttribute('ismap') is null