Add font-smoothing mixin for Wagtail, using it on tooltips

client/src/components/Draftail/Tooltip/Tooltip.scss

@@ -71,6 +71,7 @@ $tooltip-z-index: $draftail-tooltip-z-index;
 }
 
 .Tooltip__link {
+    @include font-smoothing;
     font-size: 0.875rem;
     margin-right: $controls-spacing * 4;
     display: inline-block;

wagtail/admin/static_src/wagtailadmin/scss/_mixins.scss

@@ -5,6 +5,12 @@
 // Please note that the mixins partial shouldn't include any classes. This is so
 // it can be included in any file without accidentally producing output
 
+// Turns on font-smoothing when used. Use sparingly.
+@mixin font-smoothing {
+    -webkit-font-smoothing: antialiased;
+    -moz-osx-font-smoothing: grayscale;
+}
+
 @mixin clearfix() {
     &:before,
     &:after {
@@ -86,6 +92,7 @@
 
 
 @mixin icon () {
+    @include font-smoothing;
     font-family: 'wagtail';
     font-style: normal;
     font-weight: normal;
@@ -95,8 +102,6 @@
     text-decoration: none;
     width: 1.3em;
     line-height: 1em;
-    -webkit-font-smoothing: antialiased;
-    -moz-osx-font-smoothing: grayscale;
     text-align: left;
     vertical-align: middle;
     margin-right: 0.2em;

wagtail/admin/static_src/wagtailadmin/scss/components/_messages.scss

@@ -25,11 +25,10 @@
     }
 
     > ul > li:before {
+        @include font-smoothing;
         margin-right: 0.5em;
         font-size: 1.5em;
         vertical-align: middle;
-        -webkit-font-smoothing: antialiased;
-        -moz-osx-font-smoothing: grayscale;
     }
 
     .error {

wagtail/admin/static_src/wagtailadmin/scss/components/_tabs.scss

@@ -65,6 +65,7 @@
 
     li.settings a {
         &:before {
+            @include font-smoothing;
             font-family: wagtail;
             vertical-align: middle;
             text-transform: none;
@@ -72,8 +73,6 @@
             margin-right: 0.5em;
             font-size: 1.2em;
             font-weight: normal;
-            -webkit-font-smoothing: antialiased;
-            -moz-osx-font-smoothing: grayscale;
         }
     }
 

wagtail/admin/static_src/wagtailadmin/scss/layouts/page-editor.scss

@@ -125,6 +125,7 @@ $object-title-height: 40px;
 
         &:before,
         label:before {
+            @include font-smoothing;
             text-shadow: none;
             font-family: wagtail;
             text-transform: none;
@@ -142,8 +143,6 @@ $object-title-height: 40px;
             padding: 0;
             margin: 0;
             background-color: $color-salmon;
-            -webkit-font-smoothing: antialiased;
-            -moz-osx-font-smoothing: grayscale;
         }
     }