* refactor: don't walk maps twice to remove elements
* refactor: don't walk maps twice to read elements
* refactor: don't walk maps twice to insert elements
* refactor: don't walk map 3x on UvTaskRunner timeout
* refactor: more don't-walk-maps-twice cleanup
* fixup! refactor: don't walk maps twice to insert elements
* refactor: don't walk containers twice when erasing
* refactor: omit excess lookups in RemoteObjectFreer