Add @UnsupportedAppUsage annotations

For packages:
  android.webkit

This is an automatically generated CL. See go/UnsupportedAppUsage
for more details.

Exempted-From-Owner-Approval: Mechanical changes to the codebase
which have been approved by Android API council and announced on
android-eng@

Bug: 110868826
Test: m
Change-Id: Ic22415d3e70a3b75a6418f96beb371d0445c7484
Merged-In: I41643e1e47391a12b0aed3058b3d9987a8e6ee2f