v0.6.10

JET v0.6.10

Diff since v0.6.9

Merged pull requests:

• update invalidation callback to handle invoke-backedges (#397) (@aviatesk)
• refine invalidation callback implementation (#398) (@aviatesk)
• power up builtin error report (#399) (@aviatesk)
• don't type-annotate Union{} expression (#400) (@aviatesk)