fix(compiler_cli): normalize used directives

- e.g. needed for content projection.

Closes #8677

modules/@angular/compiler_cli/integrationtest/src/projection.ts

@@ -0,0 +1,15 @@
+import {Component} from '@angular/core';
+
+@Component({
+  selector: 'comp-with-proj',
+  template: '<ng-content></ng-content>'
+})
+export class CompWithProjection {
+}
+
+@Component({
+  selector: 'main',
+  template: '<comp-with-proj><span greeting="Hello world!"></span></comp-with-proj>',
+  directives: [CompWithProjection]
+})
+export class MainComp {}