This commit introduces a new API to the ngUpgrade module, which is compatible
with AoT compilation. Primarily, it removes the dependency on reflection
over the Angular 2 metadata by introducing an API where this information
is explicitly defined, in the source code, in a way that is not lost through
AoT compilation.
This commit is a collaboration between @mhevery (who provided the original
design of the API); @gkalpak & @petebacondarwin (who implemented the
API and migrated the specs from the original ngUpgrade tests) and @alexeagle
(who provided input and review).
This commit is an starting point, there is still work to be done:
* add more documentation
* validate the API via internal projects
* align the ngUpgrade compilation of A1 directives closer to the real A1
compiler
* add more unit tests
* consider support for async `templateUrl` A1 upgraded components
Closes#12239
We changed the bootstrap order:
1. create NgZone
2. bootstrap ng1 inside NgZone and upgrade ng1 components to ng2 components.
3. bootstrap ng2 with NgZone
Note: Previous footgun behavior was: bootstrap ng2 first to extract NgZone, so that ng1 bootstrap can happen in NgZone. This meant that if ng2 bootstrap eagerly compiled a component which contained ng1 components, then we did not have complete metadata.
