Fix for cubic line chart issue when filling charts that don't start at x-index 0 (#711)
Fix for cubic line chart issue when filling charts that don't start at x-index 0 (#711)

Cubic line charts that don’t start at x-index 0 don’t fill correctly
because the fill starts at index 0 (Regular line charts don’t have that
issue). To correct this the index for the fill is taken from the data
entries (similar to regular line chart fill).
Ultimately i think the renderer should be refactored to use a common
code path for filling cubic and regular line charts.

jesseXu/Charts,GreenCom-Networks/ios-charts,ConcepterDev/ios-charts,StephenVinouze/ios-charts,MAARK/Charts,liuxuan30/ios-charts,hanquochan/Charts,SBGMobile/Charts,LiveHappier/Charts,ConcepterDev/ios-charts,danielgindi/Charts,liuxuan30/ios-charts,icecrystal23/ios-charts,liuxuan30/ios-charts,leoMehlig/Charts,jesseXu/Charts,dtrauger/Charts,Eflet/Charts,boluomeng/Charts,GreenCom-Networks/ios-charts,shujucn/ios-charts,gjpc/ios-charts,liuxuan30/Charts,leoMehlig/Charts,hanquochan/Charts,jum/Charts,koroff/Charts,franqueli/ios-charts,Shannon-s-Dreamland/Charts,ekohe/ios-charts,FreddyZeng/Charts,MAARK/Charts,FreddyZeng/Charts,jjatie/Charts,koroff/Charts,summerlove57/ios-charts,shujucn/ios-charts,franqueli/ios-charts,GreenCom-Networks/ios-charts,liuxuan30/Charts,leoMehlig/Charts,ConcepterDev/ios-charts,jum/Charts,liuxuan30/Charts,duanhjlt/ios-charts,FreddyZeng/Charts,gjpc/ios-charts,boluomeng/Charts,icecrystal23/ios-charts,jum/Charts,Eflet/Charts,danielgindi/ios-charts,SereivoanYong/Charts,jum/Charts,liuxuan30/Charts,leoMehlig/Charts,summerlove57/ios-charts,SBGMobile/Charts,danielgindi/ios-charts,boluomeng/Charts,StephenVinouze/ios-charts,jjatie/Charts,GreenCom-Networks/ios-charts,franqueli/ios-charts,leoMehlig/ios-charts,hanquochan/Charts,aelam/Charts,FreddyZeng/Charts,danielgindi/ios-charts,jesseXu/Charts,danielgindi/Charts,aelam/Charts,MAARK/Charts,danielgindi/Charts,StephenVinouze/ios-charts,convergeeducacao/Charts,SBGMobile/Charts,hanquochan/Charts,convergeeducacao/Charts,ekohe/ios-charts,Shannon-s-Dreamland/Charts,danielgindi/ios-charts,dtrauger/Charts,koroff/Charts,jjatie/Charts,LiveHappier/Charts,leoMehlig/ios-charts,aelam/Charts,Eflet/Charts,LiveHappier/Charts,StephenVinouze/ios-charts,duanhjlt/ios-charts,Eflet/Charts,ekohe/ios-charts,koroff/Charts,summerlove57/ios-charts,liuxuan30/ios-charts,danielallsopp/Charts,MAARK/Charts,leoMehlig/ios-charts,dtrauger/Charts,boluomeng/Charts,danielgindi/Charts,leoMehlig/ios-charts,icecrystal23/ios-charts,SereivoanYong/Charts,danielallsopp/Charts,duanhjlt/ios-charts,icecrystal23/ios-charts,dtrauger/Charts,shujucn/ios-charts,jjatie/Charts,gjpc/ios-charts,SereivoanYong/Charts