Fix position translation bug for wrapped lines with hard tabs

Fixes #1681

spec/display-buffer-spec.coffee

@@ -600,6 +600,13 @@ describe "DisplayBuffer", ->
       expect(displayBuffer.screenPositionForBufferPosition([0, 1])).toEqual [0, 2]
       expect(displayBuffer.bufferPositionForScreenPosition([0, 2])).toEqual [0, 1]
 
+    it "correctly translates positions on soft wrapped lines containing tabs", ->
+      buffer.setText('\t\taa  bb  cc  dd  ee  ff  gg')
+      displayBuffer.setSoftWrap(true)
+      displayBuffer.setEditorWidthInChars(10)
+      expect(displayBuffer.screenPositionForBufferPosition([0, 10], wrapAtSoftNewlines: true)).toEqual [1, 0]
+      expect(displayBuffer.bufferPositionForScreenPosition([1, 0])).toEqual [0, 10]
+
   describe ".getMaxLineLength()", ->
     it "returns the length of the longest screen line", ->
       expect(displayBuffer.getMaxLineLength()).toBe 65

src/tokenized-line.coffee

@@ -6,6 +6,7 @@ class TokenizedLine
     @tokens = @breakOutAtomicTokens(tokens, tabLength)
     @startBufferColumn ?= 0
     @text = _.pluck(@tokens, 'value').join('')
+    @bufferDelta = _.sum(_.pluck(@tokens, 'bufferDelta'))
 
   copy: ->
     new TokenizedLine({@tokens, @lineEnding, @ruleStack, @startBufferColumn, @fold})
@@ -55,7 +56,7 @@ class TokenizedLine
       @text.length
 
   getMaxBufferColumn: ->
-    @startBufferColumn + @getMaxScreenColumn()
+    @startBufferColumn + @bufferDelta
 
   softWrapAt: (column) ->
     return [new TokenizedLine([], '', [0, 0], [0, 0]), this] if column == 0
@@ -78,7 +79,7 @@ class TokenizedLine
     )
     rightFragment = new TokenizedLine(
       tokens: rightTokens
-      startBufferColumn: @startBufferColumn + column
+      startBufferColumn: @bufferColumnForScreenColumn(column)
       ruleStack: @ruleStack
       lineEnding: @lineEnding
     )