support for classes

[caridy]

note: classes are supported today if they are transformed before the transpiler kicks in, but we should also support them natively so the order of the processors should be irrelevant.

add support for classes, specifically:

export class foo {} 
export default class {}
export default class foo {}

which is (nearly) equivalent to:

export function foo () {}
export default function () {}
export default function foo () {}

Considerations:

• the current test infrastructure will not support this because those classes have to also be transformed right after the transpilation happen (@eventualbuddha, any suggestion about this?)
• although, classes are almost identical to functions, there are some formatters that might want to hoist the functions, while classes can NOT be hoisted due to the extend (system formatter hoist functions)

/cc @matthewrobb

[domenic]

which is equivalent to:

Not exactly. Classes don't hoist like function declarations do.