Fix “Unexpected CSS token” warning on Safari

Caused by `filter: progid:DXImageTransform.Microsoft.BasicImage`
css property. Since we are addressing IE >= 8 and valid HTML5 templates,
we can use `-ms-filter: "progid:DXImageTransform.Microsoft.BasicImage”`
to get the same result

Fix #5043

css/font-awesome.css

@@ -118,31 +118,31 @@
   }
 }
 .fa-rotate-90 {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=1);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=1)";
   -webkit-transform: rotate(90deg);
   -ms-transform: rotate(90deg);
   transform: rotate(90deg);
 }
 .fa-rotate-180 {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=2);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=2)";
   -webkit-transform: rotate(180deg);
   -ms-transform: rotate(180deg);
   transform: rotate(180deg);
 }
 .fa-rotate-270 {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=3);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=3)";
   -webkit-transform: rotate(270deg);
   -ms-transform: rotate(270deg);
   transform: rotate(270deg);
 }
 .fa-flip-horizontal {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=0, mirror=1);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=0, mirror=1)";
   -webkit-transform: scale(-1, 1);
   -ms-transform: scale(-1, 1);
   transform: scale(-1, 1);
 }
 .fa-flip-vertical {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=2, mirror=1);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=2, mirror=1)";
   -webkit-transform: scale(1, -1);
   -ms-transform: scale(1, -1);
   transform: scale(1, -1);

less/mixins.less

@@ -12,14 +12,14 @@
 }
 
 .fa-icon-rotate(@degrees, @rotation) {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=@rotation);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=@{rotation})";
   -webkit-transform: rotate(@degrees);
       -ms-transform: rotate(@degrees);
           transform: rotate(@degrees);
 }
 
 .fa-icon-flip(@horiz, @vert, @rotation) {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=@rotation, mirror=1);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=@{rotation}, mirror=1)";
   -webkit-transform: scale(@horiz, @vert);
       -ms-transform: scale(@horiz, @vert);
           transform: scale(@horiz, @vert);

scss/_mixins.scss

@@ -12,14 +12,14 @@
 }
 
 @mixin fa-icon-rotate($degrees, $rotation) {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=#{$rotation});
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=#{$rotation})";
   -webkit-transform: rotate($degrees);
       -ms-transform: rotate($degrees);
           transform: rotate($degrees);
 }
 
 @mixin fa-icon-flip($horiz, $vert, $rotation) {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=#{$rotation}, mirror=1);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=#{$rotation}, mirror=1)";
   -webkit-transform: scale($horiz, $vert);
       -ms-transform: scale($horiz, $vert);
           transform: scale($horiz, $vert);

src/assets/font-awesome/less/mixins.less

@@ -8,14 +8,14 @@
 }
 
 .fa-icon-rotate(@degrees, @rotation) {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=@rotation);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=@{rotation})";
   -webkit-transform: rotate(@degrees);
       -ms-transform: rotate(@degrees);
           transform: rotate(@degrees);
 }
 
 .fa-icon-flip(@horiz, @vert, @rotation) {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=@rotation, mirror=1);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=@{rotation}, mirror=1)";
   -webkit-transform: scale(@horiz, @vert);
       -ms-transform: scale(@horiz, @vert);
           transform: scale(@horiz, @vert);

src/assets/font-awesome/scss/_mixins.scss

@@ -8,14 +8,14 @@
 }
 
 @mixin fa-icon-rotate($degrees, $rotation) {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=#{$rotation});
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=#{$rotation})";
   -webkit-transform: rotate($degrees);
       -ms-transform: rotate($degrees);
           transform: rotate($degrees);
 }
 
 @mixin fa-icon-flip($horiz, $vert, $rotation) {
-  filter: progid:DXImageTransform.Microsoft.BasicImage(rotation=#{$rotation}, mirror=1);
+  -ms-filter: "progid:DXImageTransform.Microsoft.BasicImage(rotation=#{$rotation}, mirror=1)";
   -webkit-transform: scale($horiz, $vert);
       -ms-transform: scale($horiz, $vert);
           transform: scale($horiz, $vert);