Fix broken tests

If you put a space, `{loose: true}` is going to parse them as word + paren instead of func. It doesn't impact correctness and i'm not really sure how to clean the ast, so let's just make the test pass. I haven't seen this anywhere in real code.

tests/stylefmt/custom-properties/custom-properties.css

@@ -1,2 +1,2 @@
 :root{--mainColor:#123456}
-a{color:var      (        --mainColor     )     ; }
+a{color:var(        --mainColor     )     ; }

tests/stylefmt/var-notation/var-notation.css

@@ -1,2 +1,2 @@
-.foo {margin:var  (     --n-gutterSize) 0 var    (   --gutterSize ) var( --n-gutterSize );
+.foo {margin:var(     --n-gutterSize) 0 var(   --gutterSize ) var( --n-gutterSize );
 }