Attach elements to jasmine DOM

Atom migrated to using customElements from document.registerElement. Due
to this move, now there is need to attach some elements to the DOM on
some specs.

spec/tree-view-package-spec.coffee

@@ -2688,6 +2688,8 @@ describe "TreeView", ->
             dotFileView.dispatchEvent(new MouseEvent('click', {bubbles: true, detail: 1}))
 
           runs ->
+            workspaceElement = atom.views.getView(atom.workspace)
+            jasmine.attachToDOM(workspaceElement)
             atom.commands.dispatch(treeView.element, "tree-view:duplicate")
             copyDialog = atom.workspace.getModalPanels()[0].getItem()
 
@@ -2710,6 +2712,8 @@ describe "TreeView", ->
             dotFileView.dispatchEvent(new MouseEvent('click', {bubbles: true, detail: 1}))
 
           runs ->
+            workspaceElement = atom.views.getView(atom.workspace)
+            jasmine.attachToDOM(workspaceElement)
             atom.commands.dispatch(treeView.element, "tree-view:duplicate")
             copyDialog = atom.workspace.getModalPanels()[0].getItem()
 
@@ -2732,6 +2736,8 @@ describe "TreeView", ->
             atom.workspace.open('tree-view.js')
 
           runs ->
+            workspaceElement = atom.views.getView(atom.workspace)
+            jasmine.attachToDOM(workspaceElement)
             editorElement = atom.views.getView(atom.workspace.getCenter().getActivePaneItem())
             atom.commands.dispatch(editorElement, "tree-view:duplicate")
             copyDialog = atom.workspace.getModalPanels()[0].getItem()
@@ -5244,6 +5250,7 @@ describe 'Icon class handling', ->
     waitForPackageActivation()
 
     runs ->
+      jasmine.attachToDOM(workspaceElement)
       treeView = atom.packages.getActivePackage("tree-view").mainModule.getTreeViewInstance()
       files = workspaceElement.querySelectorAll('li[is="tree-view-file"]')