On a per output-unit basis, repeated large strings are shared via a
`string$` pool.
TODOs:
- don't do it with strings passed to JS() code (they might need
to be property accesses).
- tweak thresholds, using different thresholds for slow/run-once code.
Change-Id: Ib14245d9d428e52fb2ca23f34fa533de97fa2208
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/136304
Reviewed-by: Joshua Litt <joshualitt@google.com>
Commit-Queue: Stephen Adams <sra@google.com>
Stephen Adams