Twenty Seventeen: Ensure galleries display correctly in IE11.

It appears IE11 needs an explicit width for an `inline-block` parent element.

props derrickkoo, afercia.
fixes #38872.


git-svn-id: https://develop.svn.wordpress.org/trunk@39339 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-content/themes/twentyseventeen/style.css

@@ -2935,6 +2935,7 @@ object {
 	box-shadow: none;
 	background: none;
 	display: inline-block;
+	width: 100%;
 }
 
 .gallery-item a img {