Ignore CSS Custom Properties on prefix in value lookup

Author: ai

lib/declaration.js

@@ -33,7 +33,7 @@ class Declaration extends Prefixer {
         continue
       }
       if (value.includes(other)) {
-        return true
+        return value.replace(/var\([^)]+\)/, '').includes(other)
       }
     }
     return false

test/cases/user-select.css

@@ -9,3 +9,7 @@ b {
 .all {
   user-select: all;
 }
+
+.var {
+  user-select: var(--o-select);
+}

test/cases/user-select.out.css

@@ -14,3 +14,9 @@ b {
   -webkit-user-select: all;
           user-select: all;
 }
+
+.var {
+  -webkit-user-select: var(--o-select);
+      -ms-user-select: var(--o-select);
+          user-select: var(--o-select);
+}