Use buffer position when end of word isn't found

Previously if null was returned for the end of word position then
it was interpreted as 0,0 which would select the entire contents
before the current word instead of the current word.

spec/app/edit-session-spec.coffee

@@ -529,6 +529,13 @@ describe "EditSession", ->
            editSession.selectWord()
            expect(editSession.getSelectedBufferRange()).toEqual [[5, 0], [5, 6]]
 
+       describe "when the cursor is at the end of the text", ->
+         it "select the previous word", ->
+           editSession.buffer.append 'word'
+           editSession.moveCursorToBottom()
+           editSession.selectWord()
+           expect(editSession.getSelectedBufferRange()).toEqual [[12, 2], [12, 6]]
+
     describe ".setSelectedBufferRanges(ranges)", ->
       it "clears existing selections and creates selections for each of the given ranges", ->
         editSession.setSelectedBufferRanges([[[2, 2], [3, 3]], [[4, 4], [5, 5]]])

src/app/cursor.coffee

@@ -167,7 +167,7 @@ class Cursor
       if not allowNext and matchRange.start.isGreaterThan(currentBufferPosition)
         endOfWordPosition = currentBufferPosition
       stop()
-    endOfWordPosition
+    endOfWordPosition or currentBufferPosition
 
   getCurrentWordBufferRange: ->
     new Range(@getBeginningOfCurrentWordBufferPosition(allowPrevious: false), @getEndOfCurrentWordBufferPosition(allowNext: false))