refactor(core): ts’ify core

modules/angular2/src/core/annotations/annotations.ts

@@ -0,0 +1,12 @@
+/**
+ * This indirection is needed to free up Component, etc symbols in the public API
+ * to be used by the decorator versions of these annotations.
+ */
+
+export {
+  Component as ComponentAnnotation,
+  Directive as DirectiveAnnotation,
+  onDestroy,
+  onChange,
+  onAllChangesDone
+} from '../annotations_impl/annotations';