fix validation error in OOXML chart export

Change-Id: I750b33054ea0ee6202c0046a9f3947ab8bf44cd6
fix OOXML validation error with conditional formatting

Change-Id: I737b3f5bf140a0cf80fac6cae243922882cca018
fix infinite loop during export

Change-Id: I75bfafbc7343aaddbbc5c7433e28b5d4154177dc