Image fails to load on reload.

## What's the issue?
When reloading a page using the fallback process in a browser that does not support webp display, the image does not load and remains in the loading state.

## How do we reproduce the issue?
1. Access the AMP page.
2. Reload the page

## What browsers are affected?
iPhone 6(iOS13.1)
iPhone 7(iOS13.13)

In the iPhone XR(iOS14.3) environment, it worked fine.

## Which AMP version is affected?
2011252111003

Start by reproducing the AMP page reload on an affected iPhone browser that lacks WebP display support, using the fallback process described in the issue. Trace the image loading path involved in reload handling; the work is done when the image finishes loading instead of remaining in the loading state on the affected environments.

Written by the indexing model from the issue text.