Content-Security-Policy fix for the iframe init process.
Content-Security-Policy fix for the iframe init process.

Instead of using an inline event handler, attach the (simpler) event
handler before adding the iframe to the outer DOM.

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