Add deactivate to TreeView

spec/extensions/tree-view-spec.coffee

@@ -77,6 +77,11 @@ describe "TreeView", ->
 
     afterEach ->
       newTreeView.deactivate()
+  describe "when the prototypes deactivate method is called", ->
+    it "calls the deactivate on tree view instance", ->
+      spyOn(treeView, "deactivate").andCallThrough()
+      TreeView.deactivate()
+      expect(treeView.deactivate).toHaveBeenCalled()
 
     it "restores expanded directories and selected file when deserialized", ->
       treeView.find('.directory:contains(zed)').click()

src/extensions/tree-view/tree-view.coffee

@@ -19,6 +19,9 @@ class TreeView extends View
       @instance = new TreeView(rootView)
       @instance.attach()
 
+  @deactivate: () ->
+    @instance.deactivate()
+
   @serialize: ->
     @instance.serialize()