always preallocate

[TyOverby]

depends on #125

[TyOverby]

Closing in favor of #127

[ZoeyR]

Am I crazy? or is the diff of this the same as #127?

[TyOverby]

@dgriffen This is a PR that depends on #125 (which depends on #124), while #127 only depends on #124

For both of the PRs, look at the "branch target"

TyOverby  wants to merge 1 commit into inline-all-the-things from eager-prealloc

vs

TyOverby  wants to merge 1 commit into size-limit-trait from eager-prealloc-no-inline