It appears we preserve CodeSourceMap objects in obfuscated mode. They are used for building string representations of stack traces (one frame might be decoded into multiple functions) as well as for storing pc offset -> token position mappings.

This information is not necessary for the AOT runtime for correctness, only for stack traces and exception messages. We could therefore consider moving this information out of AOT snapshot, similarly to how we have an external obfuscation map.

These CodeSourceMap's sometimes take up 15% of the isolate snapshot (upwards of half a MB).