Reports over multiple domains merge/muddle results

Running on Ubuntu 18.04 on a Jenkins slave headlessly.

    -b chrome \
    -n 3 \
    --chrome.timeline true \
    --visualMetrics true \
    --visualElements true \
    --pageCompleteCheckInactivity \
    --influxdb.host <host> \
    --influxdb.database sitespeed \
    --influxdb.annotationScreenshot true \
    --s3.bucketname <bucket> \
    --s3.acl public-read \
    --s3.removeLocalResult \
    --firstParty "..regex here.." \
    --resultBaseURL <base_url> \
    https://www.google.com https://www.duckduckgo.com

If you have any differing domains in the URLs passed to sitespeed, the results in the HTML report are mixed. e.g. the domains list contains all domains for both google and duckduck.

Expectation? Tossing out some ideas.

• Generate a report for each unique host passed to sitespeed
• Could throw an error/warning if html reports are enabled and more than one domain was passed into the tool.

Reproduce the issue with the provided Docker command using google.com and duckduckgo.com, then inspect the generated HTML report and its domain lists. Determine whether separate reports or a warning is the intended outcome. Done means results from different hosts are no longer mixed, or the multi-domain limitation is clearly reported.