Polymer 3: Restore Templatizer to polymer.js

This was removed in https://crrev.com/c/1790641 since there is no more
chromium code that uses Templatizer directly. However, Templatizer is
still used by iron-list, so this needs to be restored in order to
compile pages that use iron-list (e.g. chrome://extensions).

This causes a 438 byte increase in size in polymer_bundled.min.js
(from 147272 to 147710).

Bug: 1004967
Change-Id: I51235bde1daf3155f0951f85d4ae4111af9d7bd0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1832629
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#701408}

third_party/polymer/v3_0/components-chromium/polymer/polymer_bundled.js

@@ -12912,6 +12912,126 @@ Code distributed by Google as part of the polymer project is also
 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 */
 
+/**
+ * The `Templatizer` behavior adds methods to generate instances of
+ * templates that are each managed by an anonymous `PropertyEffects`
+ * instance where data-bindings in the stamped template content are bound to
+ * accessors on itself.
+ *
+ * This behavior is provided in Polymer 2.x-3.x as a hybrid-element convenience
+ * only.  For non-hybrid usage, the `Templatize` library
+ * should be used instead.
+ *
+ * Example:
+ *
+ *     import {dom} from '@polymer/polymer/polymer_bundled.min.js';
+ *     // Get a template from somewhere, e.g. light DOM
+ *     let template = this.querySelector('template');
+ *     // Prepare the template
+ *     this.templatize(template);
+ *     // Instance the template with an initial data model
+ *     let instance = this.stamp({myProp: 'initial'});
+ *     // Insert the instance's DOM somewhere, e.g. light DOM
+ *     dom(this).appendChild(instance.root);
+ *     // Changing a property on the instance will propagate to bindings
+ *     // in the template
+ *     instance.myProp = 'new value';
+ *
+ * Users of `Templatizer` may need to implement the following abstract
+ * API's to determine how properties and paths from the host should be
+ * forwarded into to instances:
+ *
+ *     _forwardHostPropV2: function(prop, value)
+ *
+ * Likewise, users may implement these additional abstract API's to determine
+ * how instance-specific properties that change on the instance should be
+ * forwarded out to the host, if necessary.
+ *
+ *     _notifyInstancePropV2: function(inst, prop, value)
+ *
+ * In order to determine which properties are instance-specific and require
+ * custom notification via `_notifyInstanceProp`, define an `_instanceProps`
+ * object containing keys for each instance prop, for example:
+ *
+ *     _instanceProps: {
+ *       item: true,
+ *       index: true
+ *     }
+ *
+ * Any properties used in the template that are not defined in _instanceProp
+ * will be forwarded out to the Templatize `owner` automatically.
+ *
+ * Users may also implement the following abstract function to show or
+ * hide any DOM generated using `stamp`:
+ *
+ *     _showHideChildren: function(shouldHide)
+ *
+ * Note that some callbacks are suffixed with `V2` in the Polymer 2.x behavior
+ * as the implementations will need to differ from the callbacks required
+ * by the 1.x Templatizer API due to changes in the `TemplateInstance` API
+ * between versions 1.x and 2.x.
+ *
+ * @polymerBehavior
+ */
+const Templatizer = {
+
+  /**
+   * Generates an anonymous `TemplateInstance` class (stored as `this.ctor`)
+   * for the provided template.  This method should be called once per
+   * template to prepare an element for stamping the template, followed
+   * by `stamp` to create new instances of the template.
+   *
+   * @param {!HTMLTemplateElement} template Template to prepare
+   * @param {boolean=} mutableData When `true`, the generated class will skip
+   *   strict dirty-checking for objects and arrays (always consider them to
+   *   be "dirty"). Defaults to false.
+   * @return {void}
+   * @this {TemplatizerUser}
+   */
+  templatize(template, mutableData) {
+    this._templatizerTemplate = template;
+    this.ctor = templatize(template, this, {
+      mutableData: Boolean(mutableData),
+      parentModel: this._parentModel,
+      instanceProps: this._instanceProps,
+      forwardHostProp: this._forwardHostPropV2,
+      notifyInstanceProp: this._notifyInstancePropV2
+    });
+  },
+
+  /**
+   * Creates an instance of the template prepared by `templatize`.  The object
+   * returned is an instance of the anonymous class generated by `templatize`
+   * whose `root` property is a document fragment containing newly cloned
+   * template content, and which has property accessors corresponding to
+   * properties referenced in template bindings.
+   *
+   * @param {Object=} model Object containing initial property values to
+   *   populate into the template bindings.
+   * @return {TemplateInstanceBase} Returns the created instance of
+   * the template prepared by `templatize`.
+   * @this {TemplatizerUser}
+   */
+  stamp(model) {
+    return new this.ctor(model);
+  },
+
+  /**
+   * Returns the template "model" (`TemplateInstance`) associated with
+   * a given element, which serves as the binding scope for the template
+   * instance the element is contained in.  A template model should be used
+   * to manipulate data associated with this template instance.
+   *
+   * @param {HTMLElement} el Element for which to return a template model.
+   * @return {TemplateInstanceBase} Model representing the binding scope for
+   *   the element.
+   * @this {TemplatizerUser}
+   */
+  modelForElement(el) {
+    return modelForElement(this._templatizerTemplate, el);
+  }
+};
+
 /**
 @license
 Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
@@ -14902,4 +15022,4 @@ Code distributed by Google as part of the polymer project is also
 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 */
 
-export { Base, Debouncer, OptionalMutableDataBehavior, Polymer, PolymerElement, TemplateInstanceBase, afterNextRender, animationFrame, beforeNextRender, dashToCamelCase, dom, enqueueDebouncer, flush, gestures$1 as gestures, html, idlePeriod, matches, microTask, templatize, translate, useShadow };
+export { Base, Debouncer, OptionalMutableDataBehavior, Polymer, PolymerElement, TemplateInstanceBase, Templatizer, afterNextRender, animationFrame, beforeNextRender, dashToCamelCase, dom, enqueueDebouncer, flush, gestures$1 as gestures, html, idlePeriod, matches, microTask, templatize, translate, useShadow };

third_party/polymer/v3_0/polymer.js

@@ -22,4 +22,5 @@ export {OptionalMutableDataBehavior} from './lib/legacy/mutable-data-behavior.js
 export {Polymer} from './lib/legacy/polymer-fn.js';
 export {PolymerElement} from './polymer-element.js';
 export {TemplateInstanceBase, templatize} from './lib/utils/templatize.js';
+export {Templatizer} from './lib/legacy/templatizer-behavior.js';
 export {useShadow} from './lib/utils/settings.js';