Make both .scale(X) and .scale(X, Y) both work

less/mixins.less

@@ -148,31 +148,45 @@
 }
 
 // Transformations
-.rotate(@degrees) {
-  -webkit-transform: rotate(@degrees);
-      -ms-transform: rotate(@degrees); // IE9 only
-          transform: rotate(@degrees);
+.scale(@ratio) {
+  -webkit-transform: scale(@ratio);
+      -ms-transform: scale(@ratio); // IE9 only
+          transform: scale(@ratio);
+}
+.scale(@ratioX; @ratioY) {
+  -webkit-transform: scale(@ratioX, @ratioY);
+      -ms-transform: scale(@ratioX, @ratioY); // IE9 only
+          transform: scale(@ratioX, @ratioY);
+}
+.scaleX(@ratio) {
+  -webkit-transform: scaleX(@ratio);
+      -ms-transform: scaleX(@ratio); // IE9 only
+          transform: scaleX(@ratio);
+}
+.scaleY(@ratio) {
+  -webkit-transform: scaleY(@ratio);
+      -ms-transform: scaleY(@ratio); // IE9 only
+          transform: scaleY(@ratio);
 }
-.scale(@ratio; @ratio-y...) {
-  -webkit-transform: scale(@ratio, @ratio-y);
-      -ms-transform: scale(@ratio, @ratio-y); // IE9 only
-          transform: scale(@ratio, @ratio-y);
+.skew(@x; @y) {
+  -webkit-transform: skew(@x, @y);
+      -ms-transform: skewX(@x) skewY(@y); // See https://github.com/twbs/bootstrap/issues/4885; IE9+
+          transform: skew(@x, @y);
 }
 .translate(@x; @y) {
   -webkit-transform: translate(@x, @y);
       -ms-transform: translate(@x, @y); // IE9 only
           transform: translate(@x, @y);
 }
-.skew(@x; @y) {
-  -webkit-transform: skew(@x, @y);
-      -ms-transform: skewX(@x) skewY(@y); // See https://github.com/twbs/bootstrap/issues/4885; IE9+
-          transform: skew(@x, @y);
-}
 .translate3d(@x; @y; @z) {
   -webkit-transform: translate3d(@x, @y, @z);
           transform: translate3d(@x, @y, @z);
 }
-
+.rotate(@degrees) {
+  -webkit-transform: rotate(@degrees);
+      -ms-transform: rotate(@degrees); // IE9 only
+          transform: rotate(@degrees);
+}
 .rotateX(@degrees) {
   -webkit-transform: rotateX(@degrees);
       -ms-transform: rotateX(@degrees); // IE9 only