Fix vertical tabs in Safari

Current versions of Safari on OS X and iOS are still prefixed.

themes/tiddlywiki/vanilla/base.tid

@@ -968,6 +968,7 @@ canvas.tw-edit-bitmapeditor  {
 */
 
 .tw-tab-set.tw-vertical {
+	display: -webkit-flex;
 	display: flex;
 }
 
@@ -986,6 +987,7 @@ canvas.tw-edit-bitmapeditor  {
 	margin-bottom: inherit;
 	margin-right: -1px;
 	max-width: 33%;
+	-webkit-flex: 0 0 auto;
 	flex: 0 0 auto;
 }
 
@@ -1043,6 +1045,7 @@ canvas.tw-edit-bitmapeditor  {
 	padding-top: 0;
 	padding-left: 14px;
 	border-left: 1px solid <<colour tab-border>>;
+	-webkit-flex: 0 0 70%;
 	flex: 0 0 70%;
 }