Refactor dd to push a SelectLine operation on top of Delete

Delete expects to compose with a motion, which selects the text to be
deleted. SelectLine slots in cleanly to make dd delete the current line.

src/atom/editor.coffee

@@ -80,6 +80,9 @@ class Editor extends Template
     deleteChar: ->
       @aceEditor.remove 'right'
 
+    selectLine: ->
+      @aceEditor.selection.selectLine()
+
     deleteLine: ->
       @aceEditor.removeLines()
 

src/atom/vim-mode-operators.coffee

@@ -87,4 +87,9 @@ module.exports =
         column = nextLineMatch?.index or 0
       { row, column }
 
+  SelectLine: class
+    isComplete: -> true
+
+    select: (editor) ->
+      editor.selectLine()
 

src/atom/vim-mode.coffee

@@ -71,10 +71,9 @@ class VimMode
 
   delete: () ->
     if @topOperator() instanceof op.Delete
-      @topOperator().complete = true
-      @processOpStack()
+      @pushOperator(new op.SelectLine)
     else
-      @pushOperator new op.Delete()
+      @pushOperator(new op.Delete)
 
   pushOperator: (op) ->
     @opStack.push(op)