Focusing: identify annotations by tag, instead of ID

... because new and deleted annotations don't have IDs,
only tags, assigned by the bridge.

h/static/scripts/services.coffee

@@ -242,9 +242,9 @@ class Hypothesis extends Annotator
     focused = scope.focusedAnnotations ?= {}
     for a in annotations
       if state
-        focused[a.id] = true
+        focused[a.$$tag] = true
       else
-        delete focused[a.id]
+        delete focused[a.$$tag]
     this
 
   updateViewer: (annotations=[]) ->

h/templates/client/viewer.html

@@ -34,7 +34,7 @@
     </span>
   </li>
   <li class="paper thread"
-      ng-class="{'card-emphasis': focusedAnnotations[child.message.id]}"
+      ng-class="{'card-emphasis': focusedAnnotations[child.message.$$tag]}"
       deep-count="count"
       thread="child" thread-filter
       thread-collapsed="!search.query"