feat(ICU): enable ICU extraction even when when in is not used

BREAKING CHANGES:

"{" is used a a delimiter for ICU messages then it could not be used in text nodes.
"{" should be escaped as "{{ '{' }}"

Before:

    <span>some { valid } text</span>

After:

    <span>some { invalid } text<span> <!-- throw parse error -->
    <span>some {{ '{' }} valid } text</span>

modules/@angular/router-deprecated/test/integration/router_link_spec.ts

@@ -440,9 +440,9 @@ function parentCmpLoader() {
 
 @Component({
   selector: 'parent-cmp',
-  template: `{ <a [routerLink]="['./Grandchild']" class="grandchild-link">Grandchild</a>
+  template: `[ <a [routerLink]="['./Grandchild']" class="grandchild-link">Grandchild</a>
                <a [routerLink]="['./BetterGrandchild']" class="better-grandchild-link">Better Grandchild</a>
-               <router-outlet></router-outlet> }`,
+               <router-outlet></router-outlet> ]`,
   directives: ROUTER_DIRECTIVES
 })
 @RouteConfig([