Plugin 2.0 rewrite

[WarnerHooh]

Better solution for babel parameter traverse.

We had to deal with various different AST nodes after transpiled by babel presets, even some information were missing like static/private, so we are not able to fix the bug for static methods in the old implementation. The background is babel-presets are always executed before our customized plugin when traversing deeper than ClassExpression.

Now it's much easier to transform parameter decorator with a common way and easier for bug fix.