* Refactor document.js into a class
* Move public functions first
* Rename private functions
* Rename
* Rename argument
* Use instance of DocumentUtil
* Update tests
* Refactor
* Rename (test-)document.js to (test-)document-util.js
* Create FrameClient and FrameEndpoint
* Use new Frame* classes for Popup=>frame connection
* Update api.sendMessageToFrame and api.broadcastTab to include the sender's frameId
* Update FrameClient to store the frame's frameId
* Move "yomichan" object setup to a separate file
* Update script imports
* Align message handlers
* Rename Yomichan.prepare to Yomichan.ready
* Add new prepare function
* Improve isExtensionUrl
* Create member functions for ignoreElements and ignorePoint
* Create addFullscreenChangeEventListener utility
* Move popup creation management into Frontend
* Move getUrl implementation
* Remove old setup
* Remove try/catch block
* Error wrap
* Add prepare call to TextScanner
* Update depth when popup changes
* Refactor how Frontend gets PopupFactory and frameId
* Update popup preview to work
* Update popup preview frame to use the frontend's popup
* Update how nested popups are set up
* Error wrap
* Update how popups are set up on the search page
* Error wrap
* Error unwrap
* Add missing prepare
* Remove use of frontendInitializationData
* Catch and log errors
* Use new CrossFrameAPI for popup proxy communication
* Remove use of old cross-frame communication classes
* Remove use of old cross-frame communication files
* Make the crossFrame object a member of the api object
* Remove unnecessary load of /fg/css/client.css
* Replace dynamicLoader.loadStyles with dynamicLoader.loadStyle
* Replace Popup._injectStylesheet with dynamicLoader.loadStyle
* Remove unused global
* Rename PopupProxyHost to PopupFactory
* Update FrontendApiReceiver to support non-async handlers
* Make some functions non-async
* Make setCustomCss non-async
* Make setContentScale non-async
* Remove static
* Rename variables
* Pass frameId into PopupFactory's constructor
* Change FrontendApiReceiver source from popup-proxy-host to popup-factor
* Rename _invokeHostApi to _invoke
* Rename PopupProxy.getHostUrl to getUrl
