Bug 1103192 - Replace Utils.extend with Object.assign in sms
r=azasypkin, julien

Bug 1103192 - Replace Utils.extend with Object.assign in sms

Bug 1103192 - Replace Utils.extend with Object.assign in sms - Removed leftover parts of test
Merge pull request #26802 from charleyf/Bug1103192

Bug 1103192 - Replace Utils.extend with Object.assign in sms