fix unwanted line breaking of menubutton text

since the menubutton was removed from the catch-all rule that was
disrupting their margin and width

Signed-off-by: Caolán McNamara <caolan.mcnamara@collabora.com>
Change-Id: I89df97cf397af9922610faf06bd130b1011a013e

Author: caolanm

browser/css/jsdialogs.css

@@ -1971,6 +1971,7 @@ img.context-menu-icon {
 	box-sizing: border-box;
 	height: 32px;
 	line-height: normal;
+	width: max-content;
 	font-size: var(--default-font-size);
 	font-family: var(--cool-font);
 	border: 1px solid var(--color-border-dark);