This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
http://www.w3.org/TR/2013/WD-components-intro-20130606/ (the latest version) lists the document.register() signature for extensions with three arguments: var FancyButton = document.register('button', 'fancy-button', {prototype: p}); However in the spec at https://dvcs.w3.org/hg/webcomponents/raw-file/tip/spec/custom/index.html#dfn-type-extension it's listed with two arguments: document.register('x-foo', { prototype: Object.create(HTMLParagraphElement.prototype, { firstMember: { get: function() { return "foo"; }, enumerable: true, configurable: true }, // specify more members for your prototype. // ... }) }); Since Polymer also works with two arguments, I'm guessing the example in the into is wrong.
Thank you for the bug report! Fixed: <https://dvcs.w3.org/hg/webcomponents/rev/b3bb5cb82773>