iCab and all other "browsers" on iOS are skins round the built in webkit. (It would be interesting to see if and how they are effected by this bug).
Opera hasn't released its actual browser for iOS since doing so is banned by Apple's policies. Same for Mozilla. What they have released is Opera Mini which displays pages rendered by what is effectively a server-side browser.
Their mobile browser is called Opera Mobile, Opera Mini is something slightly different from a browser, for example it doesn't execute client-side javascript.
