[cfe] Remove reify runtime

Change-Id: I7f8ad03326cbdbf1e75bc3ced024f8b467f5892c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/124687
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Karl Klose <karlklose@google.com>

Author: karlklose