Fix IE8 mouse events error
Fix IE8 mouse events error

Related #319

samudiogo/cropper,salindalakmal/cropper,iacdingping/cropper,et-soft/cropper,jemmeliCss/cropper,ndtreviv/cropper,arkomlueng/cropper,itxd/cropper,liuyan5258/cropper,albertonaperijr/cropper,shinygang/cropper,OddPrints/cropper,tekinaggul/cropper,OddPrints/cropper,fengyuanchen/cropper,liuyan5258/cropper,Paulyoufu/cropper,albertonaperijr/cropper,et-soft/cropper,un33k/cropper,timothybannister/cropper,ndtreviv/cropper,tekinaggul/cropper,timothybannister/cropper,iacdingping/cropper,shinygang/cropper,Paulyoufu/cropper,arkomlueng/cropper,salindalakmal/cropper,samudiogo/cropper,bercanozcan/cropper,itxd/cropper,bercanozcan/cropper,un33k/cropper,samudiogo/cropper,jemmeliCss/cropper