IDEA-67327 Undo: Correct bulk undo processing at document end

Corrected deferred changes processing during end -> start direction.

platform/platform-impl/src/com/intellij/openapi/editor/impl/TextChangesStorage.java

@@ -243,7 +243,7 @@ public class TextChangesStorage {
       if (newChangeStart <= storedClientStart && newChangeEnd >= storedClientEnd) {
         myChanges.remove(i);
         insertionIndex = i;
-        newChangeEnd -= changeEntry.change.getText().length();
+        newChangeEnd -= changeEntry.change.getDiff();
         i--;
         continue;
       }

platform/platform-impl/testSrc/com/intellij/openapi/editor/impl/TextChangesStorageTest.java

@@ -109,6 +109,13 @@ public class TextChangesStorageTest {
     checkChanges(c("", 2, 5));
   }
 
+  @Test
+  public void adjacentDeletesFromEndToStart() {
+    delete(5, 6);
+    delete(4, 5);
+    checkChanges(c("", 4, 6));
+  }
+  
   @Test
   public void singleReplace() {
     replace("abc", 3, 4);