Fix gutter width

When you had a 1000 line file and you fold everything
into 10 lines, it would make the gutter width only large
enough for the 10 lines, so line 999 wouldnt properly
fit in the gutter.

Refs #2423

src/editor-component.coffee

@@ -41,7 +41,7 @@ EditorComponent = React.createClass
   render: ->
     {focused, fontSize, lineHeight, fontFamily, showIndentGuide, showInvisibles, visible} = @state
     {editor, cursorBlinkPeriod, cursorBlinkResumeDelay} = @props
-    maxLineNumberDigits = editor.getScreenLineCount().toString().length
+    maxLineNumberDigits = editor.getLineCount().toString().length
     invisibles = if showInvisibles then @state.invisibles else {}
     hasSelection = editor.getSelection()? and !editor.getSelection().isEmpty()