[CFE] Add uri to crashing error message when finding .packages file

TEST=test was changed.

Change-Id: I68c2041e51c66a93f00a0e2be026caef25ddb223
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/174241
Commit-Queue: Jens Johansen <jensj@google.com>
Reviewed-by: Johnni Winther <johnniwinther@google.com>

https://dart.googlesource.com/sdk/+/9b5764d05ddf09d08950084290cf7e7c6464cecb
1 file changed
tree: d810dff02b57966086476cd5e0cab3cca9d53415
  1. commits.json