[Sass] Mention mixin backtrace stuff in the changelog.
[Sass] Mention mixin backtrace stuff in the changelog.

Nzaga/sass,tangposmarvin/haml,tenderlove/sass,macressler/haml,JuanitoFatas/sass,nicklima/sass,Ahnita/sass,PMArtz92/sass,StephanieMak/sass,concord-consortium/haml,purcell/haml,ridixcr/sass,srawlins/sass,Industrys/sass,chriseppstein/haml,schneems/sass,srinivashappy/sass,liquidmetal/sass,modulexcite/sass,Industrys/sass,stanhu/haml,xzyfer/sass,lmetla/sass,DanteKaris/sass,zaru/sass,MetaAshley/sass,Andrey-Pavlov/sass,liquidmetal/sass,jaroot32/sass,briangonzalez/sass,sideci-sample/sideci-sample-haml,tangposmarvin/haml,askl56/sass,keithpitty/haml,JuanitoFatas/sass,chriseppstein/sass,OrenBochman/sass,tangposmarvin/sass,hcatlin/sass,cmpereirasi/sass,haml/haml,cmpereirasi/sass,rammy7219/sass,amatsuda/haml,14113/sass,OrenBochman/sass,amitsuroliya/sass,nazar-pc/haml,Iamronan/sass,dylannnn/sass,antonifs/sass,ridixcr/sass,StephanieMak/sass,uniba/hamldoc_ja,stanhu/haml,baiyanghese/sass,tangposmarvin/sass,Nzaga/sass,DanteKaris/sass,oss-practice/sass,saper/sass,nickg33/sass,srawlins/sass,Anshdesire/sass,PMArtz92/sass,Iamronan/sass,Galactix/sass,dylannnn/sass,nickg33/sass,nicklima/sass,haml/haml,haml/haml,jaroot32/sass,Anshdesire/sass,MetaAshley/sass,stewx/sass,Galactix/sass,antonifs/sass,dg1dd1ngs/haml,askl56/sass,HugoRLopes/sass,Ahnita/sass,danielfein/sass,schneems/sass,amitsuroliya/sass,rammy7219/sass,lmetla/sass,stewx/sass,zaru/sass,modulexcite/sass,haml/haml,hcatlin/sass,srinivashappy/sass,chriseppstein/haml,dg1dd1ngs/haml,nazar-pc/haml,keithpitty/haml,Andrey-Pavlov/sass,danielfein/sass,macressler/haml,xzyfer/sass,saper/sass,HugoRLopes/sass