[Gutter] Add ::getDomNode to LineNumberGutterComponent

src/line-number-gutter-component.coffee

@@ -18,6 +18,9 @@ class LineNumberGutterComponent
     @domNode.addEventListener 'click', @onClick
     @domNode.addEventListener 'mousedown', @onMouseDown
 
+  getDomNode: ->
+    @domNode
+
   getName: ->
     @name
 
@@ -47,6 +50,10 @@ class LineNumberGutterComponent
 
     @updateLineNumbers()
 
+  ###
+  Section: Private Methods
+  ###
+
   # This dummy line number element holds the gutter to the appropriate width,
   # since the real line numbers are absolutely positioned for performance reasons.
   appendDummyLineNumber: ->