Update comment.

src/lib/custom-style.html

@@ -146,13 +146,16 @@
         // before applying any properties. This helps ensure that all properties 
         // are defined before any are consumed.
         // Premature application of properties can occur in 2 cases:
-        // (1) A property is consumed in a style created before it is produced. 
-        // In general, we require custom properties to be defined before usage
-        // for elements so this case is only to be slightly more like native
-        // custom properties where this construction is supported.
+        // (1) A property `--foo` is consumed in a custom-style 
+        // before another custom-style produces `--foo`. 
+        // In general, we require custom properties to be defined before being
+        // used in elements so supporting this for custom-style
+        // is dubious but is slightly more like native properties where this 
+        // is supported.
         // (2) A set of in order styles (A, B) are re-ordered due to a parser 
-        // yield A wait for textContent, making B go before A. This case
-        // can occur with native or polyflled webcomponents.
+        // yield that makes A wait for textContent. This reorders its 
+        // `_apply` after B. 
+        // This case should only occur with native webcomponents.
         var self = this;
         requestAnimationFrame(function() {
           self._applyCustomProperties(e);