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(function() {
  'use strict';

  function uncurryThis(f) {
    return f.call.bind(f);
  }

  var ShadowRoot = window.ShadowRoot;
  var createShadowRoot = uncurryThis(Element.prototype.createShadowRoot);
  var ownerDocumentGetter = uncurryThis(Object.getOwnPropertyDescriptor(Node.prototype, 'ownerDocument').get);

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if (!Document.prototype.createAttributeNS) {
  Document.prototype.createAttributeNS = function(namespaceURI, qualifiedName) {
    var dummy = this.createElement('dummy');
    dummy.setAttributeNS(namespaceURI, qualifiedName, '');
    var attr = dummy.attributes[0];
    dummy.removeAttributeNode(attr);
    return attr;
  };
}

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<link rel="import" href="../core-scaffold/core-scaffold.html">
<link rel="import" href="../core-header-panel/core-header-panel.html">
<link rel="import" href="../core-menu/core-menu.html">
<link rel="import" href="../core-item/core-item.html">
<link rel="import" href="../core-icon-button/core-icon-button.html">
<link rel="import" href="../core-toolbar/core-toolbar.html">
<link rel="import" href="../core-menu/core-submenu.html">
<link rel="import" href="../google-map/google-map.html">

<polymer-element name="my-element">

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class B {
  constructor(x) {
    this.x = x;
  }
  static [Symbol.create]() {
    var o = super();
    weakMap.set(o, 123456789);  // Dom wrapper foo
    return o;
 }

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13.10.4 Runtime Semantics: Evaluation

WithStatement : with ( Expression ) Statement

1. Let val be the result of evaluating Expression.
2. Let obj be ToObject(GetValue(val)).
3. ReturnIfAbrupt(obj).
4. Let oldEnv be the running execution context’s LexicalEnvironment.
5. Let newEnv be NewObjectEnvironment(obj, oldEnv).

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// Use Gists to store code you would like to remember later on
console.log(window); // log the "window" object to the console

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At the July TC39 meeting we decided to explore removing @@create in favor of a model where super() in a [[Construct]] call creates the instance object. To correctly know how to create the instance and set the prototype a [[Construct]] call gets an implicit receiver which is the constructor function new was called with.

class Base {
  constructor() {
    var object = Object.create(new*.prototype);  // new binding needs new syntax...
                                                 // bikeshed...
    myWeakMap.set(object, myHiddenData);
    return object;
 }

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var assert = {
  equal: function(x, y) {
    if (x === y) return;
    throw new Error();
  },
  isTrue: function(x) {
    if (x) return;
    throw new Error();
  }
};

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    createPropertyAccessor: function(name, ignoreWrites) {
      var proto = this.prototype;
      var privateName = name + '_';
      var privateObservable  = name + 'Observable_';
 
      Object.defineProperty(proto, name, {
        get: function() {
          var observable = this[privateObservable];
          if (observable)
            observable.deliver();

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'use strict';
class Base {
  constructor(x) {
    this.x = x;
  }
}

let f;
class D1 extends Base {
  constructor() {