Invalidate empty lines proceeding a change event

The indent guide on empty lines will now be updated when
the non-empty line preceeding the empty lines is updated.

spec/app/editor-spec.coffee

@@ -1849,6 +1849,20 @@ describe "Editor", ->
 
         expect(editor.renderedLines.find('.line:eq(12) .indent-guide').length).toBe 0
 
+      describe "when the indentation level on a line before an empty line is changed", ->
+        it "updates the indent guide on the empty line", ->
+          editor.attachToDom()
+          config.set("editor.showIndentGuide", true)
+
+          expect(editor.renderedLines.find('.line:eq(10) .indent-guide').length).toBe 1
+          expect(editor.renderedLines.find('.line:eq(10) .indent-guide').text()).toBe '  '
+
+          editor.setCursorBufferPosition([9])
+          editor.indentSelectedRows()
+
+          expect(editor.renderedLines.find('.line:eq(10) .indent-guide').length).toBe 2
+          expect(editor.renderedLines.find('.line:eq(10) .indent-guide').text()).toBe '    '
+
   describe "gutter rendering", ->
     beforeEach ->
       editor.attachToDom(heightInLines: 5.5)

src/app/editor.coffee

@@ -1006,6 +1006,18 @@ class Editor extends View
     return [] if !@firstRenderedScreenRow? and !@lastRenderedScreenRow?
 
     intactRanges = [{start: @firstRenderedScreenRow, end: @lastRenderedScreenRow, domStart: 0}]
+
+    if @showIndentGuide
+      trailingEmptyLineChanges = []
+      for change in @pendingChanges
+        continue unless change.bufferDelta?
+        start = change.end + change.bufferDelta + 1
+        continue unless @lineForBufferRow(start) is ''
+        end = start
+        end++ while @lineForBufferRow(end + 1) is ''
+        trailingEmptyLineChanges.push({start, end, screenDelta: 0})
+        @pendingChanges.push(trailingEmptyLineChanges...)
+
     for change in @pendingChanges
       newIntactRanges = []
       for range in intactRanges