Fixing hidden infinite loop in the build pending and attach cycle (am…

…pproject#3355)

* Only do the build resource loop if we are not already in one.

* Add tests

* outside the loop set flag.

* Protect with try-catch.

* cleanup

* build new resource test.

* Only add to pending if it's not built.

* Add comments.

Fix infinite loop :( (ampproject#3310)

Small lint fixes (from pulling this into our internal codebase). (amp…

…project#3262)

Disables cross-iframe code sharing for Twitter. (ampproject#3242)

Fixes loading of tweets in browsers that do iframe throttling, because they would sometimes throttle operations that belong to a visible fame, but are attributed to the master frame.

Workaround for ampproject#3220

Fix issue with zeros when reporting access analytics (ampproject#3206)

Fix the issues with post-download upgrade (ampproject#3192)

Fix the issues with post-download upgrade (ampproject#3192)

IE: resolve the matchMedia problem (ampproject#3112)

* IE: resolve the matchMedia problem

* linter

* Protect from both min-width and max-width errors

Fix getComputedStyle=null issue on Firefox (ampproject#3103)

* Fix getComputedStyle=null issue on Firefox

* fixes

Fix issue where observeIntersection was not returning the unlisten fu… (

ampproject#3060)