Update line number padding when max digits changes

spec/editor-component-spec.coffee

@@ -188,6 +188,20 @@ describe "EditorComponent", ->
       expect(lines[4].textContent).toBe "#{nbsp}3"
       expect(lines[5].textContent).toBe "#{nbsp}•"
 
+    it "pads line numbers to be right justified based on the maximum number of line number digits", ->
+      editor.getBuffer().setText([1..10].join('\n'))
+      lineNumberNodes = toArray(node.querySelectorAll('.line-number'))
+
+      for node, i in lineNumberNodes[0..8]
+        expect(node.textContent).toBe "#{nbsp}#{i + 1}"
+      expect(lineNumberNodes[9].textContent).toBe '10'
+
+      # Removes padding when the max number of digits goes down
+      editor.getBuffer().delete([[1, 0], [2, 0]])
+      lineNumberNodes = toArray(node.querySelectorAll('.line-number'))
+      for node, i in lineNumberNodes
+        expect(node.textContent).toBe "#{i + 1}"
+
   describe "cursor rendering", ->
     it "renders the currently visible cursors", ->
       cursor1 = editor.getCursor()

src/gutter-component.coffee

@@ -17,7 +17,7 @@ GutterComponent = React.createClass
     [startRow, endRow] = renderedRowRange
     charWidth = editor.getDefaultCharWidth()
     lineHeight = editor.getLineHeight()
-    maxDigits = editor.getLastBufferRow().toString().length
+    maxDigits = editor.getScreenLineCount().toString().length
     style =
       width: charWidth * (maxDigits + 1.5)
       height: scrollHeight
@@ -76,4 +76,4 @@ LineNumberComponent = React.createClass
   iconDivHTML: '<div class="icon-right"></div>'
 
   shouldComponentUpdate: (newProps) ->
-    not isEqualForProperties(newProps, @props, 'lineHeight', 'screenRow')
+    not isEqualForProperties(newProps, @props, 'lineHeight', 'screenRow', 'maxDigits')