Index: src/wp-admin/includes/media.php
===================================================================
--- src/wp-admin/includes/media.php	(revision 42752)
+++ src/wp-admin/includes/media.php	(working copy)
@@ -1828,7 +1828,7 @@
 
 		$readonly      = ! $user_can_edit && ! empty( $field['taxonomy'] ) ? " readonly='readonly' " : '';
 		$required      = $field['required'] ? '<span class="required">*</span>' : '';
-		$required_attr = $field['required'] ? ' required' : '';
+		$required_attr = $field['required'] ? " required='required'" : '';
 		$aria_required = $field['required'] ? " aria-required='true'" : '';
 		$class         = 'compat-field-' . $id;
 		$class        .= $field['required'] ? ' form-required' : '';
@@ -2093,7 +2093,7 @@
 		<label class="screen-reader-text" for="async-upload"><?php _e( 'Upload' ); ?></label>
 		<input type="file" name="async-upload" id="async-upload" />
 		<?php submit_button( __( 'Upload' ), 'primary', 'html-upload', false ); ?>
-		<a href="#" onclick="try{top.tb_remove();}catch(e){}; return false;"><?php _e( 'Cancel' ); ?></a>
+		<a href="#" onClick="try{top.tb_remove();}catch(e){}; return false;"><?php _e( 'Cancel' ); ?></a>
 	</p>
 	<div class="clear"></div>
 <?php
@@ -2753,7 +2753,7 @@
 				<label for="src"><span class="alignleft">' . __( 'URL' ) . '</span> <span class="required">*</span></label>
 				<span class="alignright" id="status_img"></span>
 			</th>
-			<td class="field"><input id="src" name="src" value="" type="text" required aria-required="true" onblur="addExtImage.getImageData()" /></td>
+			<td class="field"><input id="src" name="src" value="" type="text" required="required" onblur="addExtImage.getImageData()" /></td>
 		</tr>
 
 		<tr>
@@ -2760,7 +2760,7 @@
 			<th scope="row" class="label">
 				<label for="title"><span class="alignleft">' . __( 'Title' ) . '</span> <span class="required">*</span></label>
 			</th>
-			<td class="field"><input id="title" name="title" value="" type="text" required aria-required="true" /></td>
+			<td class="field"><input id="title" name="title" value="" type="text" required="required" /></td>
 		</tr>
 
 		<tr class="not-image"><td></td><td><p class="help">' . __( 'Link text, e.g. &#8220;Ransom Demands (PDF)&#8221;' ) . '</p></td></tr>
@@ -2769,7 +2769,7 @@
 			<th scope="row" class="label">
 				<label for="alt"><span class="alignleft">' . __( 'Alternative Text' ) . '</span></label>
 			</th>
-			<td class="field"><input id="alt" name="alt" value="" type="text" aria-required="true" />
+			<td class="field"><input id="alt" name="alt" value="" type="text" required="required" />
 			<p class="help">' . __( 'Alt text for the image, e.g. &#8220;The Mona Lisa&#8221;' ) . '</p></td>
 		</tr>
 		' . $caption . '
@@ -3060,7 +3060,7 @@
 ?>
 	<div class="misc-pub-section misc-pub-attachment">
 		<label for="attachment_url"><?php _e( 'File URL:' ); ?></label>
-		<input type="text" class="widefat urlfield" readonly="readonly" name="attachment_url" id="attachment_url" value="<?php echo esc_attr( $att_url ); ?>" />
+		<input type="text" class="widefat urlfield" readonly name="attachment_url" id="attachment_url" value="<?php echo esc_attr( $att_url ); ?>" />
 	</div>
 	<div class="misc-pub-section misc-pub-filename">
 		<?php _e( 'File name:' ); ?> <strong><?php echo $filename; ?></strong>