That's an interesting thought. Do you really think Microsoft would fund a cross-platform browser? Do you think Apple would fund a cross-platform browser? Yahoo is close with Microsoft, so they're out if Microsoft is. Oracle and IBM aren't really consumer facing. Intel, mostly hardware. Facebook's walled garden seems to conflict with Mozilla's core mission. Adobe, possibly. Who else were you thinking of?
Based on the rumors (and partially supported by Firefox with Bing), both Microsoft and Yahoo were actively bidding against Google (for the ad revenue, presumably).
Microsoft also probably has some interest in supporting Firefox for "browser strategic" reasons (pushing back against WebKit/Blink on mobile, a partner other than Google or Apple for work with on new web standards, etc.). I find it harder to imagine Apple being interested, but perhaps that would change if Blink starts eclipsing WebKit or if they want to push iAds more. More generally, though, the point I'm making is that (almost?) all potential alternative sponsors have extensive US ties and/or interests...
