border-box property added to tabledrag-handle

Closes #2552195

core/misc/components/tabledrag.module.css

@@ -37,6 +37,8 @@ a.tabledrag-handle:hover {
   text-decoration: none;
 }
 a.tabledrag-handle .handle {
+  -webkit-box-sizing: content-box;
+  box-sizing: content-box;
   width: 14px;
   height: 14px;
   margin: -0.4em 0.5em 0;