add EditorWindowImpl.toString (diagnose EA-68632 - assert: LookupOffsets.getLookupStart)

platform/lang-impl/src/com/intellij/injected/editor/EditorWindowImpl.java

@@ -867,4 +867,9 @@ public class EditorWindowImpl extends UserDataHolderBase implements EditorWindow
   public int getPrefixTextWidthInPixels() {
     return myDelegate.getPrefixTextWidthInPixels();
   }
+
+  @Override
+  public String toString() {
+    return super.toString() + "[disposed=" + myDisposed + "; valid=" + isValid() + "]";
+  }
 }