I suppose even EB White, proto-descriptivist that he was, would of drawn the line at 've, despite the below:

"The living language is like a cow-path: it is the creation of the cows themselves, who, having created it, follow it or depart from it according to their whims or their needs. From daily use, the path undergoes change. A cow is under no obligation to stay."
-E.B. White, writer (1899-1985)