added new variables

Author: Karlasa

lib/web/css/source/lib/variables/_buttons.less

@@ -47,6 +47,9 @@
 @button__active__gradient-color-end: false;
 
 //  Primary button
+@button-primary__font-family: @button__font-family;
+@button-primary__font-size: @button__font-size;
+@button-primary__font-weight: @button__font-weight;
 @button-primary__line-height: false;
 @button-primary__width: false;
 @button-primary__margin: false;