PropertyAccessors

Update based on `PropertiesChanged` changes

lib/mixins/property-accessors.html

@@ -128,7 +128,7 @@
       constructor() {
         super();
         /** @type {number} */
-        this.__dataCounter;
+        this.__dataCounter = 0;
       }
 
       /**
@@ -163,8 +163,6 @@
        * @protected
        */
       _initializeProperties() {
-        this.__serializing = false;
-        this.__dataCounter = 0;
         if (this.__dataProto) {
           this._initializeProtoProperties(this.__dataProto);
           this.__dataProto = null;
@@ -222,24 +220,14 @@
       }
 
       /**
-       * Converts a typed JavaScript value to a string.
-       *
-       * This method is called by Polymer when setting JS property values to
-       * HTML attributes.  Users may override this method on Polymer element
-       * prototypes to provide serialization for custom types.
-       *
-       * Note: The return value of `undefined` is used as a sentinel value to
-       * indicate the attribute should be removed.
+       * Overrides PropertiesChanged implemention to serialize objects as JSON.
        *
        * @param {*} value Property value to serialize.
        * @return {string | undefined} String serialized from the provided property value.
        */
       _serializeValue(value) {
         /* eslint-disable no-fallthrough */
         switch (typeof value) {
-          case 'boolean':
-            return value ? '' : undefined;
-
           case 'object':
             if (value instanceof Date) {
               return value.toString();
@@ -252,7 +240,7 @@
             }
 
           default:
-            return value != null ? value.toString() : undefined;
+            return super._serializeValue(value);
         }
       }
 
@@ -357,30 +345,14 @@
       }
 
       /**
-       * Overrides `PropertiesChanged` implementation to only process changes
-       * if any are pending.
+       * Overrides `PropertiesChanged` implementation.
        *
        * @protected
        */
       _flushProperties() {
-        if (this.__dataPending && this.__dataOld) {
-          this.__dataCounter++;
-          super._flushProperties();
-          this.__dataCounter--;
-        }
-      }
-
-      /**
-       * Overrides implementation in PropertiesChanged to call
-       * _flushProperties to immediately process any pending changes to
-       * properties.
-       *
-       * @public
-       */
-      ready() {
-        super.ready();
-        // Run normal flush
-        this._flushProperties();
+        this.__dataCounter++;
+        super._flushProperties();
+        this.__dataCounter--;
       }
 
     }