Use source variable when getting media attribute.
Use source variable when getting media attribute.

When retrieving the media attribute from a source, use the source variable on the line above rather than using sources[j] again.
guardian/picturefill,yubin-huang/picturefill,demateu/picturefill,demateu/picturefill,guardian/picturefill,samiadelgado/picturefill,iancrowther/picturefill,scottjehl/picturefill,samiadelgado/picturefill,patrickkettner/picturefill,ddeveloperr/picturefill,iancrowther/picturefill,yufi113/picturefill,rockmandew/picturefill,yufi113/picturefill,ddeveloperr/picturefill,rockmandew/picturefill,chrismcandrew/picturefill,mcanthony/picturefill,mcanthony/picturefill,purposeindustries/picturefill,footiealf/picturefill,nucliweb/picturefill,patrickkettner/picturefill,chrismcandrew/picturefill,scottjehl/picturefill,yubin-huang/picturefill,albell/picturefill,footiealf/picturefill,purposeindustries/picturefill,albell/picturefill