Tell marker head observers if a move was caused by a buffer change

This is used by cursor to only autoscroll when the marker head is
explicitly moved, so that passive movements caused by buffer insertions
don't trigger autoscrolling.

src/app/buffer-marker.coffee

@@ -38,7 +38,7 @@ class BufferMarker
   setHeadPosition: (headPosition, options={}) ->
     @headPosition = Point.fromObject(headPosition)
     @headPosition = @buffer.clipPosition(@headPosition) if options.clip ? true
-    observer(@headPosition) for observer in @headPositionObservers
+    observer(@headPosition, !!options.bufferChanged) for observer in @headPositionObservers
     @headPosition
 
   setTailPosition: (tailPosition, options={}) ->
@@ -81,8 +81,8 @@ class BufferMarker
       [@id]
 
   handleBufferChange: (bufferChange) ->
-    @setHeadPosition(@updatePosition(@headPosition, bufferChange, false), clip: false)
-    @setTailPosition(@updatePosition(@tailPosition, bufferChange, true), clip: false) if @tailPosition
+    @setHeadPosition(@updatePosition(@headPosition, bufferChange, false), clip: false, bufferChanged: true)
+    @setTailPosition(@updatePosition(@tailPosition, bufferChange, true), clip: false, bufferChanged: true) if @tailPosition
 
   updatePosition: (position, bufferChange, isFirstPoint) ->
     { oldRange, newRange } = bufferChange

src/app/cursor.coffee

@@ -12,8 +12,8 @@ class Cursor
   needsAutoscroll: null
 
   constructor: ({@editSession, @marker}) ->
-    @editSession.observeMarkerHeadScreenPosition @marker, (screenPosition) =>
-      @needsAutoscroll ?= @isLastCursor()
+    @editSession.observeMarkerHeadScreenPosition @marker, (screenPosition, bufferChanged) =>
+      @needsAutoscroll ?= @isLastCursor() and !bufferChanged
       @trigger 'moved', screenPosition
       @editSession.trigger 'cursor-moved', screenPosition
     @needsAutoscroll = true

src/app/display-buffer.coffee

@@ -372,9 +372,9 @@ class DisplayBuffer
     @markerScreenPositionObservers[id] ?= { head: [], tail: [] }
     @cacheMarkerScreenPositions(id) unless @markerScreenPositions[id]
     @markerScreenPositionObservers[id].head.push(callback)
-    subscription = @buffer.observeMarkerHeadPosition id, (bufferPosition) =>
+    subscription = @buffer.observeMarkerHeadPosition id, (bufferPosition, bufferChanged) =>
       @cacheMarkerScreenPositions(id)
-      callback(@getMarkerHeadScreenPosition(id))
+      callback(@getMarkerHeadScreenPosition(id), bufferChanged)
 
     cancel: =>
       subscription.cancel()
@@ -392,7 +392,7 @@ class DisplayBuffer
       currentHeadPosition = @getMarkerHeadScreenPosition(id)
       unless currentHeadPosition.isEqual(head)
         @cacheMarkerScreenPositions(id)
-        observer(currentHeadPosition) for observer in @markerScreenPositionObservers[id].head
+        observer(currentHeadPosition, false) for observer in @markerScreenPositionObservers[id].head
 
   destroy: ->
     @tokenizedBuffer.destroy()