Roll engine dcbc8a820733..9e315e64659e (3 commits) (#21979)

https://github.com/flutter/engine/compare/dcbc8a820733...9e315e64659e

git log dcbc8a820733..9e315e64659e --no-merges --oneline
9e315e646 Remove entries from dart_vm_entry_points.txt and use annotations (flutter/engine#6226)
cdbe21466 Update test .gitignore (flutter/engine#6272)
dbfa8276d [fuchsia] Fixes for the Fuchsia build (flutter/engine#6273)


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bin/internal/engine.version

-dcbc8a820733f1e613ffdaad3cf1ab57d6337632
+9e315e64659ea966eba58bada2b51112b07d284c