Merge pull request #16563 from dbkaplun/dl-horizontal-breakpoint

Adds @dl-horizontal-breakpoint

less/type.less

@@ -211,7 +211,7 @@ dd {
     &:extend(.clearfix all); // Clear the floated `dt` if an empty `dd` is present
   }
 
-  @media (min-width: @grid-float-breakpoint) {
+  @media (min-width: @dl-horizontal-breakpoint) {
     dt {
       float: left;
       width: (@dl-horizontal-offset - 20);

less/variables.less

@@ -863,5 +863,7 @@
 @page-header-border-color:    @gray-lighter;
 //** Width of horizontal description list titles
 @dl-horizontal-offset:        @component-offset-horizontal;
+//** Point at which .dl-horizontal becomes horizontal
+@dl-horizontal-breakpoint:    @grid-float-breakpoint;
 //** Horizontal line color.
 @hr-border:                   @gray-lighter;