fix: put all ngc files into a single directory (#10486)

Prior to this change `ngc` would place generated files which refer
to components in the node_modules into the node_module. This is an
issue. Now all of the files are forced into a single directory
as specified in `tsconfig.json` by the `genDir` option.

see: https://docs.google.com/document/d/1OgP1RIpZ-lWUc4113J3w13HTDcW-1-0o7TuGz0tGx0g

modules/@angular/compiler/src/output/ts_emitter.ts

@@ -254,7 +254,7 @@ class _TsEmitterVisitor extends AbstractEmitterVisitor implements o.TypeVisitor
   }
 
   getBuiltinMethodName(method: o.BuiltinMethod): string {
-    var name: any /** TODO #9100 */;
+    var name: string;
     switch (method) {
       case o.BuiltinMethod.ConcatArray:
         name = 'concat';