Fix most closure warnings.

externs/polymer-externs.js

@@ -21,7 +21,7 @@
  * computed: (string | undefined),
  * reflectToAttribute: (boolean | undefined),
  * notify: (boolean | undefined),
- * observer: (string | undefined)
+ * observer: (string | function(*,*) | undefined)
  * }}
  */
 let PolymerElementPropertiesMeta;
@@ -59,6 +59,10 @@ PolymerElementConstructor.observers;
 /** @type {(!HTMLTemplateElement | string | undefined)} */
 PolymerElementConstructor.template;
 
+let PropertiesMixinConstructor = function (){};
+/** @type {(!PolymerElementProperties | undefined)} */
+PropertiesMixinConstructor.properties;
+
 /**
  * @param {!PolymerInit} init
  * @return {!function(new:HTMLElement)}

externs/polymer-internal-shared-types.js

@@ -21,7 +21,7 @@ function StampedTemplate() { }
 StampedTemplate.prototype.__noInsertionPoint;
 /** @type {!Array<!Node>} */
 StampedTemplate.prototype.nodeList;
-/** @type {!Object<string, !Node>} */
+/** @type {!Object<string, !Element>} */
 StampedTemplate.prototype.$;
 /** @type {!TemplateInfo | undefined} */
 StampedTemplate.prototype.templateInfo;

lib/legacy/legacy-element-mixin.html

@@ -483,11 +483,12 @@
        * childNodes list is the same as the element's childNodes except that
        * any `<content>` elements are replaced with the list of nodes distributed
        * to the `<content>`, the result of its `getDistributedNodes` method.
-       * @this {Element}
        * @return {Array<Node>} List of effective child nodes.
+       * @suppress {invalidCasts} LegacyElementMixin must be applied to an HTMLElement
        */
       getEffectiveChildNodes() {
-        const domApi = /** @type {Polymer.DomApi} */(Polymer.dom(this));
+        const thisEl = /** @type {Element} */ (this);
+        const domApi = /** @type {Polymer.DomApi} */(Polymer.dom(thisEl));
         return domApi.getEffectiveChildNodes();
       }
 
@@ -496,11 +497,12 @@
        * `selector`. These can be dom children or elements distributed to
        * children that are insertion points.
        * @param {string} selector Selector to run.
-       * @this {Element}
        * @return {Array<Node>} List of distributed elements that match selector.
+       * @suppress {invalidCasts} LegacyElementMixin must be applied to an HTMLElement
        */
       queryDistributedElements(selector) {
-        const domApi = /** @type {Polymer.DomApi} */(Polymer.dom(this));
+        const thisEl = /** @type {Element} */ (this);
+        const domApi = /** @type {Polymer.DomApi} */(Polymer.dom(thisEl));
         return domApi.queryDistributedElements(selector);
       }
 
@@ -601,12 +603,13 @@
        * Checks whether an element is in this element's light DOM tree.
        *
        * @param {?Node} node The element to be checked.
-       * @this {Element}
        * @return {boolean} true if node is in this element's light DOM tree.
+       * @suppress {invalidCasts} LegacyElementMixin must be applied to an HTMLElement
        */
       isLightDescendant(node) {
-        return this !== node && this.contains(node) &&
-            this.getRootNode() === node.getRootNode();
+        const thisNode = /** @type {Node} */ (this);
+        return thisNode !== node && thisNode.contains(node) &&
+          thisNode.getRootNode() === node.getRootNode();
       }
 
       /**
@@ -628,9 +631,10 @@
        * @param {string} property The css property name.
        * @return {string} Returns the computed css property value for the given
        * `property`.
+       * @suppress {invalidCasts} LegacyElementMixin must be applied to an HTMLElement
        */
       getComputedStyleValue(property) {
-        return styleInterface.getComputedStyleValue(this, property);
+        return styleInterface.getComputedStyleValue(/** @type {!Element} */(this), property);
       }
 
       // debounce

lib/mixins/element-mixin.html

@@ -80,6 +80,7 @@
    * @mixinFunction
    * @polymer
    * @appliesMixin Polymer.PropertyEffects
+   * @appliesMixin Polymer.PropertiesMixin
    * @memberof Polymer
    * @property rootPath {string} Set to the value of `Polymer.rootPath`,
    *   which defaults to the main document path
@@ -96,6 +97,7 @@
      * @constructor
      * @extends {base}
      * @implements {Polymer_PropertyEffects}
+     * @implements {Polymer_PropertiesMixin}
      */
     const polymerElementBase = Polymer.PropertiesMixin(Polymer.PropertyEffects(base));
 
@@ -191,7 +193,7 @@
      * and/or provide an advanced api for manipulating them.
      * Also consider adding warnings when an effect cannot be changed.
      *
-     * @param {PolymerElement} proto Element class prototype to add accessors
+     * @param {!PolymerElement} proto Element class prototype to add accessors
      *   and effects to
      * @param {string} name Name of the property.
      * @param {Object} info Info object from which to create property effects.
@@ -211,7 +213,7 @@
       // setup where multiple triggers for setting a property)
       // While we do have `hasComputedEffect` this is set on the property's
       // dependencies rather than itself.
-      if (info.computed  && !proto._hasReadOnlyEffect(name)) {
+      if (info.computed && !proto._hasReadOnlyEffect(name)) {
         proto._createComputedProperty(name, info.computed, allProps);
       }
       if (info.readOnly && !proto._hasReadOnlyEffect(name)) {
@@ -273,7 +275,15 @@
      */
     class PolymerElement extends polymerElementBase {
 
-      static _finalizeClass() {
+      /**
+       * Override of PropertiesMixin _finalizeClass to create observers and
+       * find the template.
+       * @return {void}
+       * @protected
+       * @override
+       * @suppress {missingProperties} Interfaces in closure do not inherit statics, but classes do
+       */
+     static _finalizeClass() {
         super._finalizeClass();
         if (this.hasOwnProperty(
           JSCompiler_renameProperty('is', this)) &&  this.is) {
@@ -298,7 +308,14 @@
 
       }
 
-      static createProperties(props) {
+      /**
+       * Override of PropertiesChanged createProperties to create accessors
+       * and property effects for all of the properties.
+       * @return {void}
+       * @protected
+       * @override
+       */
+       static createProperties(props) {
         for (let p in props) {
           createPropertyFromConfig(this.prototype, p, props[p], props);
         }
@@ -496,7 +513,7 @@
        * flushes any pending properties, and updates shimmed CSS properties
        * when using the ShadyCSS scoping/custom properties polyfill.
        *
-       * @suppress {invalidCasts}
+       * @suppress {missingProperties, invalidCasts} Super may or may not implement the callback
        */
       connectedCallback() {
         if (window.ShadyCSS && this._template) {