AMP slidescroll experiment: Hide Scrollbars (ampproject#4403)

check intersectionObserver exsits before destroy it (ampproject#4375)

Remove broken AppNexus examples. (ampproject#4214)

remove windowconfig option (ampproject#4130)

Fixing broken embed-size-* messages. (ampproject#4117)

Fixing broken embed-size-* messages. (ampproject#4117)

add prefetch method (ampproject#4062)

Gracefully handle an error during CID generation. (ampproject#4045)

Ads should work fine, when the CID cannot be provided.

Avoid lazy parsing the function body of AMP extensions. (ampproject#3979

)

Fixes ampproject#3977

Delete obsolete line

Fix ampproject#3788