✨ `amp-story-desktop-one-panel` `background-blur` Ensure img is loaded, no animation on landing (#35132)
✨ `amp-story-desktop-one-panel` `background-blur` Ensure img is loaded, no animation on landing (#35132)

* Ensure img element exists and is loaded.

* Do not animate on first load.

* Add comment.

* Update extensions/amp-story/1.0/background-blur.js

Co-authored-by: Gabriel Majoulet <61bf5be2966d6eaf52eb20c76d89ea6390af5366@google.com>

* Private var.

Co-authored-by: Gabriel Majoulet <61bf5be2966d6eaf52eb20c76d89ea6390af5366@google.com>
jpettitt/amphtml,honeybadgerdontcare/amphtml,danielrozenberg/amphtml,Gregable/amphtml,honeybadgerdontcare/amphtml,ampproject/amphtml,Gregable/amphtml,mhc-gh/amphtml,danielrozenberg/amphtml,alanorozco/amphtml,alanorozco/amphtml,honeybadgerdontcare/amphtml,ampproject/amphtml,smartadserver/amphtml,honeybadgerdontcare/amphtml,Gregable/amphtml,media-net/amphtml,honeybadgerdontcare/amphtml,Gregable/amphtml,jpettitt/amphtml,smartadserver/amphtml,danielrozenberg/amphtml,alanorozco/amphtml,jpettitt/amphtml,jpettitt/amphtml,Gregable/amphtml,ampproject/amphtml,jridgewell/amphtml,media-net/amphtml,mhc-gh/amphtml,Gregable/amphtml,Gregable/amphtml,danielrozenberg/amphtml,smartadserver/amphtml,media-net/amphtml,jpettitt/amphtml,honeybadgerdontcare/amphtml,mhc-gh/amphtml,mhc-gh/amphtml,mhc-gh/amphtml,alanorozco/amphtml,danielrozenberg/amphtml,mhc-gh/amphtml,smartadserver/amphtml,jridgewell/amphtml,jridgewell/amphtml,mhc-gh/amphtml,ampproject/amphtml,alanorozco/amphtml,honeybadgerdontcare/amphtml,smartadserver/amphtml,danielrozenberg/amphtml,jridgewell/amphtml,alanorozco/amphtml,media-net/amphtml,jpettitt/amphtml,jridgewell/amphtml,jridgewell/amphtml,alanorozco/amphtml,smartadserver/amphtml,media-net/amphtml,Gregable/amphtml,danielrozenberg/amphtml,alanorozco/amphtml,media-net/amphtml,ampproject/amphtml,jpettitt/amphtml,media-net/amphtml,ampproject/amphtml,jridgewell/amphtml,jpettitt/amphtml,danielrozenberg/amphtml,mhc-gh/amphtml,ampproject/amphtml,media-net/amphtml,ampproject/amphtml