Bug 947442 - Assert if no results have been collected.

This cause an error to be reported in the test results.
Bug 947442 - The reporter mark as a failure the lack of results.
Bug 947442 - Address review comments.
Bug 947442 - more nits. Don't collect memstat if runner isn't "host"
Bug 969217 - Improvement for the function of sharing of URLs. r=alive
Bug 971561 - [System2] Instantiable SystemBanner r=alive
Bug 973490 - [TestAgent] don't run `npm install` if `npm ink` is used r=yurenju
Bug 926852 - [Messages] Read receipts feature Gaia implementation
Bug 961950 - Replace message edit button with option menu contains delete / settings option
Bug 962649 - Be nicer to the event loop during edge gestures.
Bug 973665 - Bump version to 0.18.0 in Gaia
Merge pull request #15753 from steveck-chung/bug-961950

Bug 961950 - Replace message edit button with option menu contains delete / settings option
Merge pull request #16375 from julienw/bump-test-agent-0.18.0

Bug 973665 - Bump version to 0.18.0 in Gaia r=me
Merge pull request #16147 from hfiguiere/bug947442

Bug 947442 - Assert if no results have been collected. r=julienw
Merge pull request #16271 from KevinGrandon/bug_971561_system_banner_v2

Bug 971561 - [System2] Instantiable SystemBanner r=alive
Bug 971484 - [System2] Instantiable DialerComms r=alive
Merge pull request #16256 from KevinGrandon/bug_971484_system_dialercomms_v2

Bug 971484 - [System2] Instantiable DialerComms r=alive
Bug 971268 - Enable bookmark icon for results launched from search app
Bug 968815 - [SMS] update thread when last message is deleted, r=julienw
Merge pull request #16247 from fabi1cazenave/smsUpdateThread-bug968815

Bug 968815 - [SMS] update thread when last message is deleted, r=julienw