tree c5020c4e2e2b4fd8a2fa2cc804b4ae1692d47635
parent 2c2999643f64c25a1db1d664c5f563c878559ef2
author Zhen Chen <czhen@google.com> 1500057754 -0700
committer Zhen Chen <czhen@google.com> 1501089157 -0700

Add connectivity check from references

Make sure all objects referenced by references are reachable. Stop at
the first missing object.

Change-Id: Ifcd7392c4321b17d9290bd87f038bc62bc10dabb
Signed-off-by: Zhen Chen <czhen@google.com>