a few more comments in return

Author: dfreedm

lib/legacy/mutable-data-behavior.html

@@ -15,9 +15,8 @@
   'use strict';
 
   let mutablePropertyChange;
-  (
-    /** @suppress {missingProperties} */
-    function() {
+  /** @suppress {missingProperties} */
+  (() => {
     mutablePropertyChange = Polymer.MutableData._mutablePropertyChange;
   })();
 

lib/mixins/property-accessors.html

@@ -605,12 +605,8 @@
        * @protected
        */
       _shouldPropertyChange(property, value, old) {
-        return (
-          // Strict equality check
-          (old !== value &&
-           // This ensures (old==NaN, value==NaN) always returns false
-           (old === old || value === value))
-        );
+        // check equality, and ensure (old == NaN, value == NaN) always returns false
+        return old !== value && (old === old || value === value);
       }
 
     }