"Fix" remaining connection error handlers in Blink

This changes all remaining Mojo connection error handlers in Blink
to no-op if invoked after Blink shutdown.

TBRing haraken@ since this solution has already been discussed and
landed in several other cases, and it's a P0.

BUG=658907
TBR=haraken@chromium.org

Review-Url: https://codereview.chromium.org/2463453002
Cr-Commit-Position: refs/heads/master@{#428468}
9 files changed