Calculate newEnd correctly when line ending normalization takes place

As part of #255, we changed the
way the `onDidChangeText` and `onDidStopChanging` collected changes so
that they could avoid relying on the history (see 8a4a4d8 for more
background).

Later, in ce1964f, we improved the performance of combining the
accumulated changes by also storing the change's `newEnd`. This was,
however, slightly incorrect, as we calculated such coordinate before
normalizing line endings, thus causing the various text change events to
report inaccurate information.

With this commit we are fixing that oversight (adding also test coverage
to ensure we don't regress in the future), as well as streamlining
`applyChange`. In particular, we will now take care of normalizing lines
in `setTextInRange` instead of `applyChange`, as that's the only call
site in which normalization needs to take place.

Author: Antonio Scandurra

spec/text-buffer-spec.coffee

@@ -213,6 +213,30 @@ describe "TextBuffer", ->
           expect(buffer.lineEndingForRow(6)).toBe ''
           expect(changeEvents[1].newText).toBe "ms\r\ndo you\r\nlike\r\ndirt"
 
+          buffer.setTextInRange([[5, 1], [5, 3]], '\r')
+          expect(changeEvents[2]).toEqual({
+            oldRange: [[5, 1], [5, 3]],
+            newRange: [[5, 1], [6, 0]],
+            oldText: 'ik',
+            newText: '\r\n'
+          })
+
+          buffer.undo()
+          expect(changeEvents[3]).toEqual({
+            oldRange: [[5, 1], [6, 0]],
+            newRange: [[5, 1], [5, 3]],
+            oldText: '\r\n',
+            newText: 'ik'
+          })
+
+          buffer.redo()
+          expect(changeEvents[4]).toEqual({
+            oldRange: [[5, 1], [5, 3]],
+            newRange: [[5, 1], [6, 0]],
+            oldText: 'ik',
+            newText: '\r\n'
+          })
+
       describe "when the range's start row has no line ending (because it's the last line of the buffer)", ->
         describe "when the buffer contains no newlines", ->
           it "honors the newlines in the inserted text", ->

src/text-buffer.coffee

@@ -824,14 +824,18 @@ class TextBuffer
 
     oldRange = @clipRange(range)
     oldText = @getTextInRange(oldRange)
+
+    if normalizeLineEndings
+      normalizedEnding = @preferredLineEnding or
+        @lineEndingForRow(oldRange.start.row) or
+        @lineEndingForRow(oldRange.start.row - 1)
+      if normalizedEnding
+        newText = newText.replace(newlineRegex, normalizedEnding)
+
     change = {
-      oldStart: oldRange.start,
-      newStart: oldRange.start,
-      oldEnd: oldRange.end,
-      newEnd: traverse(oldRange.start, extentForText(newText)),
-      oldText,
-      newText,
-      normalizeLineEndings
+      oldStart: oldRange.start, oldEnd: oldRange.end,
+      newStart: oldRange.start, newEnd: traverse(oldRange.start, extentForText(newText))
+      oldText, newText
     }
     @applyChange(change, undo isnt 'skip')
 
@@ -861,25 +865,15 @@ class TextBuffer
 
   # Applies a change to the buffer based on its old range and new text.
   applyChange: (change, pushToHistory = false) ->
-    {newStart, newEnd, oldStart, oldEnd, oldText, newText, normalizeLineEndings} = change
+    {newStart, newEnd, oldStart, oldEnd, oldText, newText} = change
 
     oldExtent = traversal(oldEnd, oldStart)
-    newStart = Point.fromObject(newStart)
-    oldRange = Range(newStart, newStart.traverse(oldExtent))
+    oldRange = Range(newStart, traverse(newStart, oldExtent))
     oldRange.freeze()
 
-    # Determine how to normalize the line endings of inserted text if enabled
-    if normalizeLineEndings
-      startRow = oldRange.start.row
-      normalizedEnding = @preferredLineEnding or
-        @lineEndingForRow(startRow) or
-        @lineEndingForRow(startRow - 1)
-      if normalizedEnding
-        newText = newText.replace(newlineRegex, normalizedEnding)
-
-    newRange = Range(newStart, newEnd)
+    newExtent = traversal(newEnd, newStart)
+    newRange = Range(newStart, traverse(newStart, newExtent))
     newRange.freeze()
-    newExtent = newRange.getExtent()
 
     if pushToHistory
       change.oldExtent ?= oldExtent