I was suggesting Mozilla could help with the development. Firefox gains an engine that has a lot of other engineering hours being invested into it that can fulfill their needs.
Gecko doesn't support ios, so it wouldn't fulfill their needs here. Since Blink is known for being easier to embed then Gecko I think it would be easier for Firefox to move from Webkit to Blink than to Gecko.
Google's dominance is due to Chrome's market share. Using their browser engine doesn't affect their dominance.
So what would Firefox (or anyone) gain by Firefox ditching their engine and helping Google?