fix(sass): remove usage of slash as division

https://sass-lang.com/documentation/breaking-changes/slash-div/

src/scss/grommet-core/_base.grommet-only.scss

@@ -1,4 +1,5 @@
 // (C) Copyright 2014-2016 Hewlett Packard Enterprise Development LP
+@use "sass:math";
 
 .grommet,
 .brand-font {
@@ -23,8 +24,8 @@
   // 5. Fonts on OSX will look more consistent with other systems that do not
   //    render text using sub-pixel anti-aliasing.
 
-  font-size: ($inuit-base-font-size / 16px) * 1em;
-  line-height: $inuit-base-line-height / $inuit-base-font-size;
+  font-size: math.div($inuit-base-font-size, 16px) * 1em;
+  line-height: math.div($inuit-base-line-height, $inuit-base-font-size);
   background-color: $background-color;
   color: $text-color;
   // overflow-y: scroll; // [2]

src/scss/grommet-core/_objects.legend.scss

@@ -1,4 +1,5 @@
 // (C) Copyright 2014-2016 Hewlett Packard Enterprise Development LP
+@use "sass:math";
 
 .#{$grommet-namespace}legend {
   text-align: left;
@@ -106,7 +107,7 @@
 
 .#{$grommet-namespace}legend--large {
   font-size: $paragraph-large-font-size;
-  line-height: $paragraph-large-font-size + round($inuit-base-spacing-unit / 3);
+  line-height: $paragraph-large-font-size + round(math.div($inuit-base-spacing-unit, 3));
 
   .#{$grommet-namespace}legend__item {
     margin-bottom: quarter($inuit-base-spacing-unit);

src/scss/grommet-core/_objects.map.scss

@@ -1,7 +1,8 @@
 // (C) Copyright 2014-2016 Hewlett Packard Enterprise Development LP
+@use "sass:math";
 
-$map-stroke-width: round($inuit-base-spacing-unit / 12);
-$map-active-stroke-width: round($inuit-base-spacing-unit / 4);
+$map-stroke-width: round(math.div($inuit-base-spacing-unit, 12));
+$map-active-stroke-width: round(math.div($inuit-base-spacing-unit, 4));
 
 .#{$grommet-namespace}map {
   position: relative;

src/scss/grommet-core/_objects.meter-bar.scss

@@ -1,20 +1,21 @@
 // (C) Copyright 2014-2016 Hewlett Packard Enterprise Development LP
+@use "sass:math";
 
 // BAR
 
 // For each size of meter, we calculate the proportional cross dimension
 $meter-bar-cross-xsmall:
-  round($inuit-base-spacing-unit * ($size-xsmall / $size-small));
+  round($inuit-base-spacing-unit * math.div($size-xsmall, $size-small));
 $meter-bar-cross-small:
-  round($inuit-base-spacing-unit * ($size-small / $size-small));
+  round($inuit-base-spacing-unit * math.div($size-small, $size-small));
 $meter-bar-cross-medium:
-  round($inuit-base-spacing-unit * ($size-medium / $size-small));
+  round($inuit-base-spacing-unit * math.div($size-medium, $size-small));
 $meter-bar-cross-large:
-  round($inuit-base-spacing-unit * ($size-large / $size-small));
+  round($inuit-base-spacing-unit * math.div($size-large, $size-small));
 $meter-bar-cross-xlarge:
-  round($inuit-base-spacing-unit * ($size-xlarge / $size-small));
+  round($inuit-base-spacing-unit * math.div($size-xlarge, $size-small));
 $meter-bar-cross-default:
-  round($inuit-base-spacing-unit * ($meter-size-default / $size-small));
+  round($inuit-base-spacing-unit * math.div($meter-size-default, $size-small));
 
 @include keyframes(draw-meter-bar-small) {
   0% {

src/scss/grommet-core/_objects.meter.scss

@@ -1,11 +1,12 @@
 // (C) Copyright 2014-2016 Hewlett Packard Enterprise Development LP
+@use "sass:math";
 
 $meter-size-default: $size-small;
 
-$meter-slice-width: round($inuit-base-spacing-unit / 6);
-$meter-slice-active-width: round($inuit-base-spacing-unit / 2);
+$meter-slice-width: round(math.div($inuit-base-spacing-unit, 6));
+$meter-slice-active-width: round(math.div($inuit-base-spacing-unit, 2));
 $meter-threshold-slice-width: $meter-slice-width;
-$meter-indicator-width: round($inuit-base-spacing-unit / 6);
+$meter-indicator-width: round(math.div($inuit-base-spacing-unit, 6));
 
 $meter-label-width: double($inuit-base-spacing-unit);
 $meter-active-offset: round($inuit-base-spacing-unit * 1.5);

src/scss/grommet-core/_objects.pulse.scss

@@ -1,4 +1,6 @@
 // (C) Copyright 2014-2016 Hewlett Packard Enterprise Development LP
+@use "sass:math";
+
 $base-size: double($inuit-base-spacing-unit);
 
 @mixin scale-up-fade-out($duration, $delay) {
@@ -56,7 +58,7 @@ $base-size: double($inuit-base-spacing-unit);
     width: $base-size;
     height: $base-size;
     border-radius: $base-size;
-    padding: $inuit-base-spacing-unit / 2;
+    padding: math.div($inuit-base-spacing-unit, 2);
     background-color: nth($brand-accent-colors, 1);
     stroke: nth($brand-grey-colors, 1);
   }

src/scss/grommet-core/_objects.sun-burst.scss

@@ -1,7 +1,8 @@
 // (C) Copyright 2016 Hewlett Packard Enterprise Development LP
+@use "sass:math";
 
 $sun-burst-slice-width: round($inuit-base-spacing-unit);
-$sun-burst-small-slice-width: round($inuit-base-spacing-unit / 2);
+$sun-burst-small-slice-width: round(math.div($inuit-base-spacing-unit, 2));
 $sun-burst-large-slice-width: round($inuit-base-spacing-unit * 1.5);
 $sun-burst-xlarge-slice-width: round($inuit-base-spacing-unit * 3);
 

src/scss/grommet-core/_objects.topology.scss

@@ -1,9 +1,10 @@
 // (C) Copyright 2014-2016 Hewlett Packard Enterprise Development LP
+@use "sass:math";
 
 $outer-pad: round($inuit-base-spacing-unit * 2);
 $inner-pad: round($inuit-base-spacing-unit * 0.25);
-$topology-stroke-width: round($inuit-base-spacing-unit / 12);
-$topology-active-stroke-width: round($inuit-base-spacing-unit / 4);
+$topology-stroke-width: round(math.div($inuit-base-spacing-unit, 12));
+$topology-active-stroke-width: round(math.div($inuit-base-spacing-unit, 4));
 
 .#{$grommet-namespace}topology {
   position: relative;

src/scss/grommet-core/_tools.input.scss

@@ -1,4 +1,5 @@
 // (C) Copyright 2014-2018 Hewlett Packard Enterprise Development LP
+@use "sass:math";
 
 // We use mixins for some text styles to make it easier to modularize the
 // CSS. For example `.grommet p` uses the same styles as
@@ -50,7 +51,7 @@
 }
 
 $button-vertical-padding:
-  round($inuit-base-spacing-unit / 3) - $button-border-width;
+  round(math.div($inuit-base-spacing-unit, 3)) - $button-border-width;
 $button-horizontal-padding:
   round($inuit-base-spacing-unit) - $button-border-width;