Hide overlay play button if it can't be shown without clipping

third_party/WebKit/LayoutTests/media/controls-cast-button-narrow.html

Index: third_party/WebKit/LayoutTests/media/controls-cast-button-narrow.html
diff --git a/third_party/WebKit/LayoutTests/media/controls-cast-button-narrow.html b/third_party/WebKit/LayoutTests/media/controls-cast-button-narrow.html
index 5196286f4f0dd5fc27dce30cfc451f8809fead48..a49674853ccc196487cc08f9a9ecc410651f44ac 100644
--- a/third_party/WebKit/LayoutTests/media/controls-cast-button-narrow.html
+++ b/third_party/WebKit/LayoutTests/media/controls-cast-button-narrow.html
@@ -41,12 +41,5 @@ async_test(function(t) {
             }));
         }));
     });
-
-    function isVisible(button) {
-        var computedStyle = getComputedStyle(button);
-        return computedStyle.display !== "none" &&
-               computedStyle.display !== "hidden" &&
-               computedStyle.visibility === "visible";
-    }
 });
 </script>