Handle changes inside of folds.

Don't emit an event since nothing changes (since it's all folded). But update the position of the fold's end marker so when it's unfolded, things render correctly.

spec/atom/line-folder-spec.coffee

@@ -223,7 +223,20 @@ describe "LineFolder", ->
         expect(folder.lineForScreenRow(4).text).toBe '    while(items.length > 0) {...abc}'
 
     describe "when the old range is inside a fold", ->
-      it "does not trigger a change event, but ensures the change is present when the fold is destroyed", ->
+      it "does not trigger a change event, but updates the fold and ensures the change is present when the fold is destroyed", ->
+        buffer.change(new Range([4, 29], [6, 0]), 'abc')
+
+        expect(folder.lineForScreenRow(4).text).toBe '    while(items.length > 0) {...}...concat(sort(right));'
+        expect(changeHandler).not.toHaveBeenCalled()
+
+        fold1.destroy()
+        expect(folder.lineForScreenRow(4).text).toBe '    while(items.length > 0) {abc      current < pivot ? left.push(current) : right.push(current);'
+        expect(folder.lineForScreenRow(5).text).toBe '    }...concat(sort(right));'
+
+        expect(changeHandler).toHaveBeenCalled()
+        [[event]] = changeHandler.argsForCall
+        expect(event.oldRange).toEqual [[4, 0], [4, 56]]
+        expect(event.newRange).toEqual [[4, 0], [5, 28]]
 
     describe "when the old range surrounds a fold", ->
       it "removes the fold and replaces the placeholder with the new text", ->