fix Issue with fa-rotate-* in IE9 #3527

css/font-awesome.css

@@ -157,6 +157,13 @@
   -o-transform: scale(1, -1);
   transform: scale(1, -1);
 }
+:root .fa-rotate-90,
+:root .fa-rotate-180,
+:root .fa-rotate-270,
+:root .fa-flip-horizontal,
+:root .fa-flip-vertical {
+  filter: none;
+}
 .fa-stack {
   position: relative;
   display: inline-block;

less/rotated-flipped.less

@@ -7,3 +7,14 @@
 
 .@{fa-css-prefix}-flip-horizontal { .fa-icon-flip(-1, 1, 0); }
 .@{fa-css-prefix}-flip-vertical   { .fa-icon-flip(1, -1, 2); }
+
+// Hook for IE8-9
+// -------------------------
+
+:root .@{fa-css-prefix}-rotate-90,
+:root .@{fa-css-prefix}-rotate-180,
+:root .@{fa-css-prefix}-rotate-270,
+:root .@{fa-css-prefix}-flip-horizontal,
+:root .@{fa-css-prefix}-flip-vertical {
+  filter: none;
+}

scss/_rotated-flipped.scss

@@ -7,3 +7,14 @@
 
 .#{$fa-css-prefix}-flip-horizontal { @include fa-icon-flip(-1, 1, 0); }
 .#{$fa-css-prefix}-flip-vertical   { @include fa-icon-flip(1, -1, 2); }
+
+// Hook for IE8-9
+// -------------------------
+
+:root .#{$fa-css-prefix}-rotate-90,
+:root .#{$fa-css-prefix}-rotate-180,
+:root .#{$fa-css-prefix}-rotate-270,
+:root .#{$fa-css-prefix}-flip-horizontal,
+:root .#{$fa-css-prefix}-flip-vertical {
+  filter: none;
+}

src/assets/font-awesome/less/rotated-flipped.less

@@ -10,3 +10,14 @@
 
 .@{fa-css-prefix}-flip-horizontal { .fa-icon-flip(-1, 1, 0); }
 .@{fa-css-prefix}-flip-vertical   { .fa-icon-flip(1, -1, 2); }
+
+// Hook for IE8-9
+// -------------------------
+
+:root .@{fa-css-prefix}-rotate-90,
+:root .@{fa-css-prefix}-rotate-180,
+:root .@{fa-css-prefix}-rotate-270,
+:root .@{fa-css-prefix}-flip-horizontal,
+:root .@{fa-css-prefix}-flip-vertical {
+  filter: none;
+}

src/assets/font-awesome/scss/_rotated-flipped.scss

@@ -10,3 +10,14 @@
 
 .#{$fa-css-prefix}-flip-horizontal { @include fa-icon-flip(-1, 1, 0); }
 .#{$fa-css-prefix}-flip-vertical   { @include fa-icon-flip(1, -1, 2); }
+
+// Hook for IE8-9
+// -------------------------
+
+:root .#{$fa-css-prefix}-rotate-90,
+:root .#{$fa-css-prefix}-rotate-180,
+:root .#{$fa-css-prefix}-rotate-270,
+:root .#{$fa-css-prefix}-flip-horizontal,
+:root .#{$fa-css-prefix}-flip-vertical {
+  filter: none;
+}