Add ViewRegistry::pollAfterNextUpdate

Closes #6196

spec/view-registry-spec.coffee

@@ -137,6 +137,21 @@ describe "ViewRegistry", ->
       advanceClock(registry.documentPollingInterval)
       expect(events).toEqual ['write', 'read', 'poll', 'poll']
 
+    it "polls the document after updating when ::pollAfterNextUpdate() has been called", ->
+      events = []
+      registry.pollDocument -> events.push('poll')
+      registry.updateDocument -> events.push('write')
+      registry.readDocument -> events.push('read')
+      frameRequests.shift()()
+      expect(events).toEqual ['write', 'read']
+
+      events = []
+      registry.pollAfterNextUpdate()
+      registry.updateDocument -> events.push('write')
+      registry.readDocument -> events.push('read')
+      frameRequests.shift()()
+      expect(events).toEqual ['write', 'read', 'poll']
+
   describe "::pollDocument(fn)", ->
     it "calls all registered reader functions on an interval until they are disabled via a returned disposable", ->
       spyOn(window, 'setInterval').andCallFake(fakeSetInterval)

src/view-registry.coffee

@@ -178,6 +178,9 @@ class ViewRegistry
       @documentPollers = @documentPollers.filter (poller) -> poller isnt fn
       @stopPollingDocument() if @documentPollers.length is 0
 
+  pollAfterNextUpdate: ->
+    @performDocumentPollAfterUpdate = true
+
   clearDocumentRequests: ->
     @documentReaders = []
     @documentWriters = []
@@ -194,6 +197,7 @@ class ViewRegistry
     writer() while writer = @documentWriters.shift()
     reader() while reader = @documentReaders.shift()
     @performDocumentPoll() if @performDocumentPollAfterUpdate
+    @performDocumentPollAfterUpdate = false
 
   startPollingDocument: ->
     @pollIntervalHandle = window.setInterval(@performDocumentPoll, @documentPollingInterval)
@@ -205,6 +209,5 @@ class ViewRegistry
     if @documentUpdateRequested
       @performDocumentPollAfterUpdate = true
     else
-      @performDocumentPollAfterUpdate = false
       poller() for poller in @documentPollers
       return