Convert polymer transformers to be a "global" transformer #422
Description
<img src="https://avatars.githubusercontent.com/u/2049220?v=3" align="left" width="96" height="96"hspace="10"> Issue by sigmundch
Originally opened as dart-lang/sdk#20267
We want to use a global transformation for several reasons:
- make some packages easier to use: we can remove the default transformer from smoke, which sometimes surprises people.
- faster load: no need to transform code that is loaded by transfomers (we might be able to also remove the self-transformer in polymer itself)
- make it possible to run the compiler lazily and only when needed in pub-serve (skip some of it for dartium)
- open the option of only using the polymer-transformer in the final app, not on each widget-package. Currently setting up the transformer section is not very intuitive if you have elements in multiple packages.