Add Navigation API (positive)

Fixes #543

activities.json

@@ -946,6 +946,18 @@
     "title": "Mixed Content",
     "url": "https://w3c.github.io/webappsec-mixed-content/"
   },
+  {
+    "ciuName": null,
+    "description": "The navigation API provides a web application-focused way of managing same-origin same-frame history entries and navigations.",
+    "id": "navigation-api",
+    "mozBugUrl": "https://bugzilla.mozilla.org/show_bug.cgi?id=1777171",
+    "mozPosition": "positive",
+    "mozPositionDetail": "There are various details that we're not sure about in the spec and we'd like to continue reviewing and submit feedback about issues we find. But the API as a whole is a good improvement for implementing SPAs over the status quo.",
+    "mozPositionIssue": 543,
+    "org": "WHATWG",
+    "title": "Navigation API",
+    "url": "https://github.com/whatwg/html/pull/8502"
+  },
   {
     "ciuName": null,
     "description": "The Network Error Logging spec enables website to declare a reporting policy that can be used to report encountered network errors that prevented it from successfully loading its requested resources.",