* Weather, shifting battlefronts delay removal of toxins
* Syria agreed to scrap chemical arms under Russia-US deal
* Russia, China plan to escort Western ships (Releads with OPCW saying delay is likely)
By Georgina Prodhan
VIENNA, Dec 28 (Reuters) - The removal of deadly toxins from Syria under an international effort to rid the nation of its chemical arsenal will likely miss a Dec. 31...