Allow element to work without attaching it to DOM

spec/pane-container-element-spec.coffee

@@ -10,7 +10,6 @@ describe "PaneContainerElement", ->
 
       paneAxis = new PaneAxis
       paneAxisElement = new PaneAxisElement().initialize(paneAxis, atom)
-      jasmine.attachToDOM(paneAxisElement)
 
       expect(childTagNames()).toEqual []
 
@@ -42,8 +41,6 @@ describe "PaneContainerElement", ->
         'atom-pane-axis'
       ]
 
-      paneAxisElement.remove()
-
     it "transfers focus to the next pane if a focused pane is removed", ->
       container = new PaneContainer(config: atom.config, confirm: atom.confirm.bind(atom))
       containerElement = atom.views.getView(container)
@@ -63,7 +60,6 @@ describe "PaneContainerElement", ->
     it "builds appropriately-oriented atom-pane-axis elements", ->
       container = new PaneContainer(config: atom.config, confirm: atom.confirm.bind(atom))
       containerElement = atom.views.getView(container)
-      jasmine.attachToDOM(containerElement)
 
       pane1 = container.getActivePane()
       pane2 = pane1.splitRight()
@@ -84,8 +80,6 @@ describe "PaneContainerElement", ->
       expect(verticalPanes[0]).toBe atom.views.getView(pane2)
       expect(verticalPanes[1]).toBe atom.views.getView(pane3)
 
-      containerElement.remove()
-
   describe "when the resize element is dragged ", ->
     [container, containerElement] = []
 

src/pane-axis-element.coffee

@@ -3,7 +3,17 @@ PaneResizeHandleElement = require './pane-resize-handle-element'
 
 class PaneAxisElement extends HTMLElement
   attachedCallback: ->
-    @subscriptions = @subscribeToModel()
+    @subscriptions ?= @subscribeToModel()
+    @childAdded({child, index}) for child, index in @model.getChildren()
+
+  detachedCallback: ->
+    @subscriptions.dispose()
+    @subscriptions = null
+    @childRemoved({child}) for child in @model.getChildren()
+
+  initialize: (@model, {@views}) ->
+    throw new Error("Must pass a views parameter when initializing TextEditorElements") unless @views?
+    @subscriptions ?= @subscribeToModel()
     @childAdded({child, index}) for child, index in @model.getChildren()
 
     switch @model.getOrientation()
@@ -11,21 +21,6 @@ class PaneAxisElement extends HTMLElement
         @classList.add('horizontal', 'pane-row')
       when 'vertical'
         @classList.add('vertical', 'pane-column')
-
-  detachedCallback: ->
-    @subscriptions.dispose()
-    @subscriptions = null
-    @childRemoved({child}) for child in @model.getChildren()
-
-    switch @model.getOrientation()
-      when 'horizontal'
-        @classList.remove('horizontal', 'pane-row')
-      when 'vertical'
-        @classList.remove('vertical', 'pane-column')
-
-  initialize: (@model, {@views}) ->
-    throw new Error("Must pass a views parameter when initializing TextEditorElements") unless @views?
-
     this
 
   subscribeToModel: ->