Ömer Sinan Ağacan authored Feb 05, 2019 and Marge Bot committed Mar 06, 2019

In the concurrent nonmoving collector we will need the ability to call
`traverseWeakPtrList` concurrently with minor generation collections.
This global state stands in the way of this. However, refactoring it
away is straightforward since this list only persists the length of a
single GC.