Reduced some redundancy in the selection normalization logic and added some more comments.
Reduced some redundancy in the selection normalization logic and added some more comments.

endjin/tinymce,toxalot/tinymce,jashua212/tinymce,nikolas/tinymce,danielpunkass/tinymce,shilpi230/tinymce,shilpi230/tinymce,MediehusetTek/tinymce,henrythewasp/tinymce,aduth/tinymce,sachgits/tinymce,cclaerhout/tinymce,VioletLife/tinymce,rxl194/tinymce,Shopify/tinymce,adaptiffdesigns/tinymce,adaptiffdesigns/tinymce,FernCreek/tinymce,MediehusetTek/tinymce,toxalot/tinymce,kencheung/tinymce,rxl194/tinymce,ikuchmin/tinymce,FernCreek/tinymce,Kindling/tinymce,dziemian007/tinymce,gencer/tinymce,danielpunkass/tinymce,jtark/tinymce,howanghk/tinymce,fillabs/TinySpecMCE,tinymce/tinymce,jashua212/tinymce,leofeyer/tinymce,sachgits/tinymce,1099511627776/tinymce,TeamupCom/tinymce,howanghk/tinymce,fhchina/tinymce,Zimbra/tinymce,ice8lue/tinymce,sjbufton/tinymce,ETSI-CTI/TinySpecMCE,rbecheras/tinymce,support-dot-com/tinymce,fashionsun/tinymce,nbcp/tinymce,leofeyer/tinymce,bsuh/tinymce,danchr/tinymce,VioletLife/tinymce,danchr/tinymce,support-dot-com/tinymce,gencer/tinymce,nikolas/tinymce,ice8lue/tinymce,rednose-public/tinymce,kencheung/tinymce,gabixdev/tinymce,Razzwan/tinymce,cclaerhout/tinymce,simachewh/tinymce,aduth/tinymce,blakewallan/tinymce,Kindling/tinymce,Razzwan/tinymce,enfold/tinymce,widgetfactory/tinymce,pmpl-5/tinymce,pmpl-5/tinymce,1099511627776/tinymce,simachewh/tinymce,rednose-public/tinymce,nbcp/tinymce,Zimbra/tinymce,collective/tinymce,rbecheras/tinymce,sjbufton/tinymce,widgetfactory/tinymce,fillabs/TinySpecMCE,ChristophKaser/tinymce,endjin/tinymce,ikuchmin/tinymce,blakewallan/tinymce,M4R7iNP/tinymce,gabixdev/tinymce,TeamupCom/tinymce,tinymce/tinymce,mplank/tinymce,ChristophKaser/tinymce,bsuh/tinymce,ETSI-CTI/TinySpecMCE,danielpunkass/tinymce,jtark/tinymce,tinymce/tinymce,enfold/tinymce,M4R7iNP/tinymce,henrythewasp/tinymce,mplank/tinymce,collective/tinymce,fhchina/tinymce,dziemian007/tinymce,FernCreek/tinymce,fashionsun/tinymce