All errors for existing fields have been detected and suppressed with a
`!` assertion.
Issue/24571 is tracking proper clean up of those instances.
One-line change required in ivy/compilation.ts, because it appears that
the new syntax causes tsickle emitted node to no longer track their
original sourceFiles.
PR Close#24572
The source map does not currently work with the transformer pipeline.
It will be re-enabled after TypeScript 2.4 is made the min version.
To revert to the former compiler, use the `disableTransformerPipeline` in
tsconfig.json:
```
{
"angularCompilerOptions": {
"disableTransformerPipeline": true
}
}
```
