ART: Remove RegisterNativeMethods special-casing

Use the regular RegisterNatives, instead. This ensures JNI table
changes work correctly on boot.

This is a minimal change. Cleanup is relegated to a future CL.

Bug: 62065808
Test: m test-art-host
Change-Id: I2d8c76b88f078afbcfe5ff77a7085848bdf2b388