Unnamed repository; edit this file 'description' to name the repository.
Auto merge of #154614 - nnethercote:streamline-CachingSourceMapView, r=JonathanBrouwer
Streamline `CachingSourceMapView`
`CachingSourceMapView` is home to some pretty ugly, low-level, repetitive code. We can do better. Details in individual commits.
r? @JonathanBrouwer
