DevTools: report problems with heap snapshot into the DevTools' console

The only way to see the errors was to open DevTools for DevTools which is inconvenient.

BUG=426389

Review URL: https://codereview.chromium.org/680893002

git-svn-id: svn://svn.chromium.org/blink/trunk@184456 bbb929c8-8fbe-4397-9dbb-9b2b20218538