Add position on Web Components (#227)

This covers the four initial pieces of Web Components, as discussed in #60. Some historical discussion can be found at https://hacks.mozilla.org/2014/12/mozilla-and-web-components/ and https://hacks.mozilla.org/2015/06/the-state-of-web-components/.

Closes #60.

activities.json

@@ -131,6 +131,17 @@
     "title": "Constructable Stylesheet Objects",
     "url": "https://wicg.github.io/construct-stylesheets/"
   },
+  {
+    "ciuName": null,
+    "description": "A way to create new HTML elements implemented through JavaScript.",
+    "mozBugUrl": null,
+    "mozPosition": "worth prototyping",
+    "mozPositionDetail": "A welcome successor to XBL!",
+    "mozPositionIssue": 60,
+    "org": "WHATWG",
+    "title": "Custom elements",
+    "url": "https://html.spec.whatwg.org/multipage/custom-elements.html#custom-elements"
+  },
   {
     "ciuName": null,
     "description": "This will allow custom elements to have \"default\" accessibility semantics, analogous to how built-in elements have \"implicit\" or \"native\" semantics.",
@@ -164,6 +175,17 @@
     "title": "Feature Policy",
     "url": "https://wicg.github.io/feature-policy"
   },
+  {
+    "ciuName": "imports",
+    "description": "HTML Imports are a way to include and reuse HTML documents in other HTML documents.",
+    "mozBugUrl": null,
+    "mozPosition": "harmful",
+    "mozPositionDetail": "Mozilla anticipated that JavaScript modules would change the landscape here and would rather invest in evolving that, e.g., through HTML Modules. Having a single mechanism to deal with dependencies rather than several, potentially conflicting systems, seems preferable.",
+    "mozPositionIssue": 60,
+    "org": "W3C",
+    "title": "HTML Imports",
+    "url": "http://www.w3.org/TR/2016/WD-html-imports-20160225"
+  },
   {
     "ciuName": null,
     "description": "This document defines a set of Fetch metadata request headers that aim to provide servers with enough information to make a priori decisions about whether or not to service a request based on the way it was made, and the context in which it will be used.",
@@ -296,6 +318,17 @@
     "title": "Service binding and parameter specification via the DNS (DNS SVCB and HTTPSSVC)",
     "url": "https://tools.ietf.org/html/draft-nygren-dnsop-svcb-httpssvc"
   },
+  {
+    "ciuName": null,
+    "description": "A way to give a node in the DOM a hidden subtree in which the children of the node can be inserted.",
+    "mozBugUrl": null,
+    "mozPosition": "worth prototyping",
+    "mozPositionDetail": "A welcome successor to XBL!",
+    "mozPositionIssue": 60,
+    "org": "WHATWG",
+    "title": "Shadow trees (formerly known as Shadow DOM)",
+    "url": "https://dom.spec.whatwg.org/#shadow-trees"
+  },
   {
     "ciuName": null,
     "description": "This document specifies how a server can send an HTTP request/ response pair, known as an exchange, with signatures that vouch for that exchange's authenticity. These signatures can be verified against an origin's certificate to establish that the exchange is authoritative for an origin even if it was transferred over a connection that isn't. The signatures can also be used in other ways described in the appendices. These signatures contain countermeasures against downgrade and protocol-confusion attacks.",
@@ -460,5 +493,16 @@
     "org": "WHATWG",
     "title": "enterkeyhint attribute",
     "url": "https://html.spec.whatwg.org/multipage/interaction.html#attr-enterkeyhint"
+  },
+  {
+    "ciuName": null,
+    "description": "The template element is used to declare fragments of HTML that can be cloned and inserted in the document by script.",
+    "mozBugUrl": null,
+    "mozPosition": "worth prototyping",
+    "mozPositionDetail": "A reasonable addition to HTML (and XML), if not somewhat taxing on the parser.",
+    "mozPositionIssue": 60,
+    "org": "WHATWG",
+    "title": "template element",
+    "url": "https://html.spec.whatwg.org/multipage/scripting.html#the-template-element"
   }
 ]