Turns flow comment syntax into pure flow syntax.
See the flow blog for flow comment syntax. This is intended to be paired with the flow comments babel plugin in order to fix problems with comments having their position correctly restored in otherwise 'lossless' code transforms.
Comments are not first class citizens in current JS ASTs so until a CST or appropriately detailed AST is invented, this will turn your pretend flow into true flow so it can be correctly transformed by babel.