Replace S.addCometAtEnd with S.addComet.

S.addComet takes a LiftCometActor instead of an Elem. It
replaces the private trackComet that simply added an entry
to S.requestCometVersions.

Additionally, this makes server-side actors and roundtrip
streaming promises work again.

web/webkit/src/main/scala/net/liftweb/http/LiftMerge.scala

@@ -196,12 +196,6 @@ private[http] trait LiftMerge {
         headChildren += nl
       }
 
-      for {
-        e <- S.cometAtEnd()
-      } {
-        _fixHtml(e, true, false, false, true, false, false, true, false)
-      }
-
       // Appends ajax script to body
       if (LiftRules.autoIncludeAjaxCalc.vend().apply(this)) {
         bodyChildren +=

web/webkit/src/main/scala/net/liftweb/http/LiftSession.scala

@@ -2356,9 +2356,7 @@ class LiftSession(private[http] val _contextPath: String, val uniqueId: String,
 
       ca ! PerformSetupComet2(Empty)
 
-      val node: Elem = ca.buildSpan(NodeSeq.Empty)
-
-      S.addCometAtEnd(node)
+      S.addComet(ca)
 
       ca ! SetDeltaPruner(lastWhenDeltaPruner)
 
@@ -2828,9 +2826,7 @@ class LiftSession(private[http] val _contextPath: String, val uniqueId: String,
 
       ca ! SetDeltaPruner(lastWhenDeltaPruner)
 
-      val node: Elem = ca.buildSpan(NodeSeq.Empty)
-
-      S.addCometAtEnd(node)
+      S.addComet(ca)
 
       val currentReq: Box[Req] = S.request.map(_.snapshot)
 

web/webkit/src/main/scala/net/liftweb/http/S.scala

@@ -362,7 +362,11 @@ trait S extends HasParams with Loggable with UserAgentCalculator {
    */
   private object _tailTags extends TransientRequestVar(new ListBuffer[Elem])
 
-  private object _cometTags extends TransientRequestVar(new ListBuffer[Elem])
+  // Set of CometVersionPairs for comets that should be tracked on
+  // the page that is currently being rendered or that called this AJAX
+  // callback.
+  private[http] object requestCometVersions extends TransientRequestVar[Set[CometVersionPair]](Set.empty)
+
 
   private object p_queryLog extends TransientRequestVar(new ListBuffer[(String, Long)])
   private object p_notice extends TransientRequestVar(new ListBuffer[(NoticeType.Value, NodeSeq, Box[String])])
@@ -797,14 +801,12 @@ trait S extends HasParams with Loggable with UserAgentCalculator {
    */
   def atEndOfBody(): List[Elem] = _tailTags.is.toList
 
-  def addCometAtEnd(elem: Elem): Unit = _cometTags.is += elem
-
-  // Set of CometVersionPairs for comets that should be tracked on
-  // the page that is currently being rendered or that called this AJAX
-  // callback.
-  private[http] object requestCometVersions extends TransientRequestVar[Set[CometVersionPair]](Set.empty)
-
-  private def trackComet(cometActor: LiftCometActor) = {
+  /**
+   * Add a comet to the list of comets that should be registered to
+   * receive updates on the page currently being rendered or on the page
+   * that invoked the currently running callback.
+   */
+  def addComet(cometActor: LiftCometActor): Unit = {
     requestCometVersions.set(
       requestCometVersions.is + CVP(cometActor.uniqueId, cometActor.lastListenerTime)
     )
@@ -832,7 +834,7 @@ trait S extends HasParams with Loggable with UserAgentCalculator {
       cometActor <- session.findOrCreateComet(cometType, cometName, cometHtml, cometAttributes)
     } yield {
       if (receiveUpdatesOnPage)
-        trackComet(cometActor)
+        addComet(cometActor)
 
       cometActor
     }
@@ -859,14 +861,12 @@ trait S extends HasParams with Loggable with UserAgentCalculator {
       cometActor <- session.findOrCreateComet[T](cometName, cometHtml, cometAttributes)
     } yield {
       if (receiveUpdatesOnPage)
-        trackComet(cometActor)
+        addComet(cometActor)
 
       cometActor
     }
   }
 
-  def cometAtEnd(): List[Elem] = _cometTags.is.toList
-
   /**
    * Sometimes it's helpful to accumute JavaScript as part of servicing
    * a request.  For example, you may want to accumulate the JavaScript