Removed toLowerCase function call so the function name remains the same

when used with a mixin and add test for rotateX

test/less/css-3.less

@@ -11,6 +11,7 @@
 }
 .other {
   -moz-transform: translate(0, 11em) rotate(-90deg);
+  transform: rotateX(45deg);
 }
 .item[data-cra_zy-attr1b-ut3=bold] {
   font-weight: bold;