Remove Class.forName uses from reflection-based wrappers.

Object.getClass returns the implementation class, which has all the
methods, so we don't need Class.forName.

Bug: 229268202
Test: adb shell pm art optimize-package -m speed -f \
  com.google.android.youtube
Ignore-AOSP-First: ART Services.
Change-Id: If5deb179c84ad9ee617538627bccebb5535ea407
3 files changed