Index: wp-includes/class-wp-editor.php
===================================================================
--- wp-includes/class-wp-editor.php	(revision 19896)
+++ wp-includes/class-wp-editor.php	(working copy)
@@ -45,6 +45,10 @@
 		self::$this_tinymce = ( $set['tinymce'] && user_can_richedit() );
 		self::$this_quicktags = (bool) $set['quicktags'];
 
+		// Disable tinymce for the Amazon Silk browser, which doesn't support contentEditable.
+		if( isset( $_SERVER['HTTP_USER_AGENT'] ) && ( false !== strpos( $_SERVER['HTTP_USER_AGENT'], '; Silk/' ) ) )
+			self::$this_tinymce = false;
+
 		if ( self::$this_tinymce )
 			self::$has_tinymce = true;