Use `WellKnownClasses` in reflection. am: 343077add4

Original change: https://android-review.googlesource.com/c/platform/art/+/2969531

Change-Id: I4711e9c569096fe758fa52e36c1f35c7470fe950
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>