fix #970 by rendering full page if bbox is larger than native page size when zooming mode is fit to content*
fix #970
by rendering full page if bbox is larger than native page size when
zooming mode is fit to content*

frankyifei/koreader,Markismus/koreader,houqp/koreader,koreader/koreader,koreader/koreader,chrox/koreader,chihyang/koreader,robert00s/koreader,ashhher3/koreader,mwoz123/koreader,mihailim/koreader,pazos/koreader,Hzj-jie/koreader,noname007/koreader,Frenzie/koreader,poire-z/koreader,NiLuJe/koreader,poire-z/koreader,NiLuJe/koreader,ashang/koreader,NickSavage/koreader,apletnev/koreader,Frenzie/koreader,lgeek/koreader