Finalized rotate/flip in [less].

less/_mixins.less

@@ -4,7 +4,7 @@
 .fa-icon() {
 
   display: inline-block;
-  font: normal normal normal @wi-font-size-base / 1 WeatherIcons; // shortening font declaration
+  font: normal normal normal @wi-font-size-base/1 WeatherIcons; // shortening font declaration
   font-size: inherit; // can't have font-size inherit on line above, so need to override
   text-rendering: auto; // optimizelegibility throws things off #1094
   -webkit-font-smoothing: antialiased;
@@ -12,11 +12,16 @@
   transform: translate(0, 0); // ensures no half-pixel rendering in firefox
 }
 
-.wi-icon-rotate(@degrees, @rotation) {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=@rotation);
-  -webkit-transform: rotate(@degrees);
-      -ms-transform: rotate(@degrees);
-          transform: rotate(@degrees);
+.wi-icon-rotate(@degrees) {
+
+  & when (mod(@degrees, 90) = 0) {
+
+    @rotation: @degrees / 90;
+    filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=@rotation);
+  }
+  -webkit-transform: rotate(~"@{degrees}deg");
+      -ms-transform: rotate(~"@{degrees}deg");
+          transform: rotate(~"@{degrees}deg");
 }
 
 .wi-icon-flip(@horiz, @vert, @rotation) {

less/_rotated-flipped.less

@@ -1,2 +1,47 @@
 // rotated and flipped icons
 // -------------------------
+
+@rotations-requiring-ie-fix:
+  "flip-horizontal",
+  "flip-vertical";
+@z: '';
+
+.calculateRotations(@i) when (@i >= 0) {
+
+  // iterate
+  .calculateRotations((@i - 1));
+
+  @z: ~"@{wi-css-prefix}-rotate-@{i}";
+
+  .@{z} when (mod(@i, @wi-rotate-by) = 0) {
+
+    .wi-icon-rotate(@i);
+  }
+}
+.calculateRotations(359);
+
+.@{wi-css-prefix}-flip-horizontal { .wi-icon-flip(-1, 1, 0); }
+.@{wi-css-prefix}-flip-vertical   { .wi-icon-flip(1, -1, 2); }
+
+// ie 8-9 fix
+// -------------------------
+
+// todo: check on assigning an array of selectors to the selector instead of this
+//       unnecessary duplication of code
+
+:root  {
+
+  .calculateIEFixes(@i) when (@i >= 0) {
+
+  // iterate
+  .calculateIEFixes((@i - 1));
+
+    @z: ~"@{wi-css-prefix}-rotate-@{i}";
+
+    .@{z} when (mod(@i, 90) = 0) {
+
+      filter: none;
+    }
+  }
+  .calculateIEFixes(359);
+}