With this change ngc now accepts a `-w` or a `--watch`
command-line option that will automatically perform a
recompile whenever any source files change on disk.
PR Close#18818
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
}
}
```