Guards all uses of onTriggerObservable until we can figure out more detail (#12547)
Guards all uses of onTriggerObservable until we can figure out more detail (#12547)

* Guards all uses of onTriggerObservable until we can figure out more detail

* Warns when onTriggerObservable_ is unexpectedly null

* Renames this.ampdoc to this.ampdoc_

* Undoes piping ampdoc around

sriramkrish85/amphtml,yandex-pcode/amphtml,danielrozenberg/amphtml,BenDz/amphtml,zhangsu/amphtml,danielrozenberg/amphtml,sebastianbenz/amphtml,shawnbuso/amphtml,tlong2/amphtml,mhc-gh/amphtml,luciancrasovan/amphtml,zhouyx/amphtml,nexxtv/amphtml,aghassemi/amphtml,tlong2/amphtml,clawr/amphtml,smartadserver/amphtml,BenDz/amphtml,luciancrasovan/amphtml,alanorozco/amphtml,ampproject/amphtml,Gregable/amphtml,media-net/amphtml,clawr/amphtml,prateekbh/amphtml,camelburrito/amphtml,smartadserver/amphtml,ampproject/amphtml,alanorozco/amphtml,sebastianbenz/amphtml,taboola/amphtml,src-code/amphtml,Gregable/amphtml,smartadserver/amphtml,jmadler/amphtml,widespace-os/amphtml,luciancrasovan/amphtml,kamtschatka/amphtml,sebastianbenz/amphtml,taboola/amphtml,sharethrough/amphtml,shawnbuso/amphtml,zhangsu/amphtml,dotandads/amphtml,kamtschatka/amphtml,bpaduch/amphtml,techhtml/amphtml,honeybadgerdontcare/amphtml,honeybadgerdontcare/amphtml,erwinmombay/amphtml,cory-work/amphtml,donttrustthisbot/amphtml,media-net/amphtml,voyagegroup/amphtml,engtat/amphtml,sriramkrish85/amphtml,alanorozco/amphtml,nexxtv/amphtml,jmadler/amphtml,widespace-os/amphtml,camelburrito/amphtml,media-net/amphtml,widespace-os/amphtml,cvializ/amphtml,rsimha-amp/amphtml,dotandads/amphtml,nexxtv/amphtml,jmadler/amphtml,sriramkrish85/amphtml,ampproject/amphtml,luciancrasovan/amphtml,camelburrito/amphtml,adup-tech/amphtml,pedjoni8/amphtml,pedjoni8/amphtml,smartadserver/amphtml,Gregable/amphtml,prateekbh/amphtml,engtat/amphtml,luciancrasovan/amphtml,voyagegroup/amphtml,techhtml/amphtml,jpettitt/amphtml,sebastianbenz/amphtml,BenDz/amphtml,luciancrasovan/amphtml,camelburrito/amphtml,jpettitt/amphtml,jpettitt/amphtml,pedjoni8/amphtml,yieldmo/amphtml,taboola/amphtml,bpaduch/amphtml,cory-work/amphtml,yandex-pcode/amphtml,bpaduch/amphtml,engtat/amphtml,rsimha-amp/amphtml,powdercloud/amphtml,jridgewell/amphtml,lannka/amphtml,pedjoni8/amphtml,donttrustthisbot/amphtml,danielrozenberg/amphtml,prateekbh/amphtml,lannka/amphtml,yieldbot/amphtml,cory-work/amphtml,ampproject/amphtml,bpaduch/amphtml,donttrustthisbot/amphtml,laterpay/amphtml,Gregable/amphtml,zhouyx/amphtml,widespace-os/amphtml,mhc-gh/amphtml,cory-work/amphtml,sharethrough/amphtml,techhtml/amphtml,dotandads/amphtml,yieldmo/amphtml,shawnbuso/amphtml,engtat/amphtml,honeybadgerdontcare/amphtml,Gregable/amphtml,koshka/amphtml,yieldbot/amphtml,tlong2/amphtml,dotandads/amphtml,zhouyx/amphtml,yandex-pcode/amphtml,lannka/amphtml,Gregable/amphtml,lannka/amphtml,danielrozenberg/amphtml,chaveznvg/amphtml,zhangsu/amphtml,aghassemi/amphtml,erwinmombay/amphtml,yieldmo/amphtml,shawnbuso/amphtml,pedjoni8/amphtml,Gregable/amphtml,chaveznvg/amphtml,smartadserver/amphtml,jpettitt/amphtml,media-net/amphtml,camelburrito/amphtml,mhc-gh/amphtml,yieldmo/amphtml,alanorozco/amphtml,cvializ/amphtml,laterpay/amphtml,yieldmo/amphtml,powdercloud/amphtml,media-net/amphtml,honeybadgerdontcare/amphtml,taboola/amphtml,Gregable/amphtml,voyagegroup/amphtml,dotandads/amphtml,tlong2/amphtml,erwinmombay/amphtml,ampproject/amphtml,sharethrough/amphtml,yieldmo/amphtml,adup-tech/amphtml,alanorozco/amphtml,prateekbh/amphtml,cory-work/amphtml,jridgewell/amphtml,cvializ/amphtml,engtat/amphtml,danielrozenberg/amphtml,sharethrough/amphtml,widespace-os/amphtml,donttrustthisbot/amphtml,zhouyx/amphtml,danielrozenberg/amphtml,yandex-pcode/amphtml,prateekbh/amphtml,alanorozco/amphtml,yieldbot/amphtml,alanorozco/amphtml,rsimha-amp/amphtml,chaveznvg/amphtml,danielrozenberg/amphtml,laterpay/amphtml,koshka/amphtml,taboola/amphtml,erwinmombay/amphtml,mhc-gh/amphtml,jpettitt/amphtml,voyagegroup/amphtml,voyagegroup/amphtml,rsimha-amp/amphtml,nexxtv/amphtml,kamtschatka/amphtml,chaveznvg/amphtml,laterpay/amphtml,sebastianbenz/amphtml,yieldbot/amphtml,lannka/amphtml,koshka/amphtml,rsimha-amp/amphtml,techhtml/amphtml,rsimha-amp/amphtml,laterpay/amphtml,jridgewell/amphtml,jmadler/amphtml,kamtschatka/amphtml,src-code/amphtml,camelburrito/amphtml,laterpay/amphtml,donttrustthisbot/amphtml,yieldmo/amphtml,rsimha-amp/amphtml,sharethrough/amphtml,luciancrasovan/amphtml,src-code/amphtml,clawr/amphtml,cvializ/amphtml,powdercloud/amphtml,shawnbuso/amphtml,clawr/amphtml,sriramkrish85/amphtml,shawnbuso/amphtml,clawr/amphtml,jmadler/amphtml,bpaduch/amphtml,voyagegroup/amphtml,pedjoni8/amphtml,cory-work/amphtml,yandex-pcode/amphtml,BenDz/amphtml,powdercloud/amphtml,camelburrito/amphtml,honeybadgerdontcare/amphtml,voyagegroup/amphtml,zhouyx/amphtml,engtat/amphtml,nexxtv/amphtml,media-net/amphtml,zhouyx/amphtml,jridgewell/amphtml,lannka/amphtml,yieldbot/amphtml,aghassemi/amphtml,mhc-gh/amphtml,yieldbot/amphtml,widespace-os/amphtml,honeybadgerdontcare/amphtml,media-net/amphtml,src-code/amphtml,nexxtv/amphtml,chaveznvg/amphtml,ampproject/amphtml,donttrustthisbot/amphtml,cvializ/amphtml,prateekbh/amphtml,powdercloud/amphtml,zhangsu/amphtml,zhangsu/amphtml,mhc-gh/amphtml,taboola/amphtml,adup-tech/amphtml,kamtschatka/amphtml,adup-tech/amphtml,kamtschatka/amphtml,jmadler/amphtml,powdercloud/amphtml,sriramkrish85/amphtml,nexxtv/amphtml,aghassemi/amphtml,honeybadgerdontcare/amphtml,techhtml/amphtml,donttrustthisbot/amphtml,alanorozco/amphtml,src-code/amphtml,adup-tech/amphtml,koshka/amphtml,zhangsu/amphtml,bpaduch/amphtml,yandex-pcode/amphtml,shawnbuso/amphtml,dotandads/amphtml,media-net/amphtml,mhc-gh/amphtml,techhtml/amphtml,danielrozenberg/amphtml,clawr/amphtml,koshka/amphtml,taboola/amphtml,erwinmombay/amphtml,ampproject/amphtml,jridgewell/amphtml,clawr/amphtml,engtat/amphtml,koshka/amphtml,mhc-gh/amphtml,yandex-pcode/amphtml,prateekbh/amphtml,smartadserver/amphtml,sharethrough/amphtml,adup-tech/amphtml,chaveznvg/amphtml,src-code/amphtml,erwinmombay/amphtml,jridgewell/amphtml,BenDz/amphtml,aghassemi/amphtml,aghassemi/amphtml,jridgewell/amphtml,tlong2/amphtml,bpaduch/amphtml,BenDz/amphtml,lannka/amphtml,cvializ/amphtml,jpettitt/amphtml,sriramkrish85/amphtml,jpettitt/amphtml,sebastianbenz/amphtml,jpettitt/amphtml,powdercloud/amphtml,ampproject/amphtml,tlong2/amphtml,zhouyx/amphtml,cory-work/amphtml