Instead of going through debugger agent, this patch implements
console.assert pause similar to debugger statement and OOM break.

New test uncovered a bug, where pause on exceptions state mix up
between different context groups. Added a TODO to fix it.

BUG=chromium:590878

Review-Url: https://codereview.chromium.org/2916363002
Cr-Commit-Position: refs/heads/master@{#45711}