Previously, the transitive scopes of an NgModuleDef were computed
during execution of the @NgModule decorator. This meant that JIT-
compiled modules could only import other JIT-compiled modules, as
the import mechanism relied on the calculation of transitive scopes
to already have happened for the imported module.
This change moves computation of transitive scopes to a function
`transitiveScopesFor` (and makes it lazy). This opens the door for
AOT -> JIT or JIT -> AOT imports, as transitive scopes for AOT
modules can be calculated when needed by JIT, and AOT modules can
also write expressions that call `transitiveScopesFor` when
importing a JIT-compiled module.
PR Close#24334
This commit adds a mechanism by which the @angular/core annotations
for @Component, @Injectable, and @NgModule become decorators which,
when executed at runtime, trigger just-in-time compilation of their
associated types. The activation of these decorators is configured
by the ivy_switch mechanism, ensuring that the Ivy JIT engine does
not get included in Angular bundles unless specifically requested.
PR Close#23833
Alex Rickabaugh
Miško Hevery