🐛 Create image pixel in onload event handler of iframe (#27204)
🐛 Create image pixel in onload event handler of iframe (#27204)

* Create image pixel in onload event handler of iframe

* Bind event handler before appending to body

* Don't use `this`
mhc-gh/amphtml,ampproject/amphtml,zhouyx/amphtml,Gregable/amphtml,zhouyx/amphtml,Gregable/amphtml,smartadserver/amphtml,zhouyx/amphtml,nexxtv/amphtml,smartadserver/amphtml,lannka/amphtml,jridgewell/amphtml,yandex-pcode/amphtml,voyagegroup/amphtml,danielrozenberg/amphtml,media-net/amphtml,honeybadgerdontcare/amphtml,mhc-gh/amphtml,sharethrough/amphtml,yandex-pcode/amphtml,honeybadgerdontcare/amphtml,jpettitt/amphtml,alanorozco/amphtml,nexxtv/amphtml,mhc-gh/amphtml,prateekbh/amphtml,taboola/amphtml,taboola/amphtml,zhouyx/amphtml,Gregable/amphtml,rsimha-amp/amphtml,zhouyx/amphtml,voyagegroup/amphtml,honeybadgerdontcare/amphtml,mhc-gh/amphtml,jridgewell/amphtml,rsimha-amp/amphtml,yandex-pcode/amphtml,rsimha-amp/amphtml,Gregable/amphtml,yandex-pcode/amphtml,sharethrough/amphtml,jmadler/amphtml,ampproject/amphtml,voyagegroup/amphtml,alanorozco/amphtml,alanorozco/amphtml,jridgewell/amphtml,adup-tech/amphtml,yandex-pcode/amphtml,adup-tech/amphtml,media-net/amphtml,ampproject/amphtml,alanorozco/amphtml,prateekbh/amphtml,jridgewell/amphtml,nexxtv/amphtml,danielrozenberg/amphtml,voyagegroup/amphtml,media-net/amphtml,rsimha-amp/amphtml,jpettitt/amphtml,alanorozco/amphtml,media-net/amphtml,adup-tech/amphtml,rsimha-amp/amphtml,mhc-gh/amphtml,prateekbh/amphtml,voyagegroup/amphtml,lannka/amphtml,jpettitt/amphtml,voyagegroup/amphtml,smartadserver/amphtml,alanorozco/amphtml,media-net/amphtml,mhc-gh/amphtml,jridgewell/amphtml,jmadler/amphtml,lannka/amphtml,jpettitt/amphtml,danielrozenberg/amphtml,ampproject/amphtml,prateekbh/amphtml,media-net/amphtml,jpettitt/amphtml,nexxtv/amphtml,jridgewell/amphtml,danielrozenberg/amphtml,adup-tech/amphtml,alanorozco/amphtml,honeybadgerdontcare/amphtml,ampproject/amphtml,yandex-pcode/amphtml,nexxtv/amphtml,Gregable/amphtml,danielrozenberg/amphtml,danielrozenberg/amphtml,rsimha-amp/amphtml,ampproject/amphtml,honeybadgerdontcare/amphtml,jmadler/amphtml,Gregable/amphtml,zhouyx/amphtml,lannka/amphtml,honeybadgerdontcare/amphtml,nexxtv/amphtml,taboola/amphtml,zhouyx/amphtml,alanorozco/amphtml,taboola/amphtml,sharethrough/amphtml,sharethrough/amphtml,smartadserver/amphtml,adup-tech/amphtml,yandex-pcode/amphtml,Gregable/amphtml,smartadserver/amphtml,honeybadgerdontcare/amphtml,jpettitt/amphtml,prateekbh/amphtml,Gregable/amphtml,media-net/amphtml,jmadler/amphtml,taboola/amphtml,mhc-gh/amphtml,sharethrough/amphtml,lannka/amphtml,sharethrough/amphtml,jmadler/amphtml,voyagegroup/amphtml,lannka/amphtml,ampproject/amphtml,taboola/amphtml,smartadserver/amphtml,jpettitt/amphtml,taboola/amphtml,mhc-gh/amphtml,danielrozenberg/amphtml,jpettitt/amphtml,rsimha-amp/amphtml,adup-tech/amphtml,nexxtv/amphtml,jridgewell/amphtml,prateekbh/amphtml,prateekbh/amphtml,jmadler/amphtml,ampproject/amphtml,media-net/amphtml,danielrozenberg/amphtml,lannka/amphtml