Annotate more return types as !defined

lib/legacy/legacy-element-mixin.js

@@ -1198,7 +1198,7 @@ export const LegacyElementMixin = dedupingMixin((base) => {
      *
      * @param {string} methodName Method name to associate with message
      * @param {...*} args Array of strings or objects to log
-     * @return {Array} Array with formatting information for `console`
+     * @return {!Array} Array with formatting information for `console`
      *   logging.
      * @override
      */

lib/legacy/polymer.dom.js

@@ -113,7 +113,7 @@ class DomApiNative {
   /**
    * Returns the root node of this node.  Equivalent to `getRootNode()`.
    *
-   * @return {Node} Top most element in the dom tree in which the node
+   * @return {!Node} Top most element in the dom tree in which the node
    * exists. If the node is connected to a document this is either a
    * shadowRoot or the document; otherwise, it may be the node
    * itself or a node or document fragment containing it.

lib/mixins/properties-mixin.js

@@ -17,8 +17,8 @@ import { PropertiesChanged } from './properties-changed.js';
  * Creates a copy of `props` with each property normalized such that
  * upgraded it is an object with at least a type property { type: Type}.
  *
- * @param {Object} props Properties to normalize
- * @return {Object} Copy of input `props` with normalized properties that
+ * @param {!Object} props Properties to normalize
+ * @return {!Object} Copy of input `props` with normalized properties that
  * are in the form {type: Type}
  * @private
  */

lib/mixins/property-effects.js

@@ -590,7 +590,7 @@ function getComputedOrder(inst) {
  *
  * @param {!Polymer_PropertyEffects} inst The instance to generate dependency
  *   counts for.
- * @return {Object} Object containing `counts` map (property-to-dependency
+ * @return {!Object} Object containing `counts` map (property-to-dependency
  *   count) and pre-populated `ready` array of properties that had zero
  *   dependencies.
  */
@@ -985,7 +985,7 @@ function addNotifyListener(node, inst, binding) {
  * @param {boolean|Object=} dynamicFn Boolean or object map indicating whether
  *   method names should be included as a dependency to the effect. Note,
  *   defaults to true if the signature is static (sig.static is true).
- * @return {Object} Effect metadata for this method effect
+ * @return {!Object} Effect metadata for this method effect
  * @private
  */
 function createMethodEffect(model, sig, type, effectFn, methodInfo, dynamicFn) {
@@ -2167,7 +2167,7 @@ export const PropertyEffects = dedupingMixin(superClass => {
      * @param {number} start Index from which to start removing/inserting.
      * @param {number=} deleteCount Number of items to remove.
      * @param {...*} items Items to insert into array.
-     * @return {Array} Array of removed items.
+     * @return {!Array} Array of removed items.
      * @public
      */
     splice(path, start, deleteCount, ...items) {
@@ -2439,7 +2439,7 @@ export const PropertyEffects = dedupingMixin(superClass => {
      * @param {!Array<!MethodArg>} args Array of argument metadata
      * @param {string} path Property/path name that triggered the method effect
      * @param {Object} props Bag of current property changes
-     * @return {Array<*>} Array of argument values
+     * @return {!Array<*>} Array of argument values
      * @private
      */
     _marshalArgs(args, path, props) {