Flip the order of some values in a calc (#2643)

This fixes build crashes in CRA thanks to a parser bug that explodes
when it encounters the original order (but inverted is fine)

UNRELEASED.md

@@ -10,6 +10,7 @@
 ### Bug fixes
 
 - Fixed scrolling with scrollbar not working in Popover when content changes on scroll ([#2627](https://github.com/Shopify/polaris-react/pull/2627))
+- Work around a build crash when using create-react-app due to a bug in css parsing in `postcss-custom-properties` ([#2643](https://github.com/Shopify/polaris-react/pull/2643))
 
 ### Documentation
 

src/styles/shared/_controls.scss

@@ -110,10 +110,10 @@
       &::before {
         content: '';
         position: absolute;
-        top: calc(var(--control-border-width) * -1);
-        right: calc(var(--control-border-width) * -1);
-        bottom: calc(var(--control-border-width) * -1);
-        left: calc(var(--control-border-width) * -1);
+        top: calc(-1 * var(--control-border-width));
+        right: calc(-1 * var(--control-border-width));
+        bottom: calc(-1 * var(--control-border-width));
+        left: calc(-1 * var(--control-border-width));
         border-radius: var(--p-border-radius-base);
         background-color: var(--p-action-interactive);
         opacity: 0;