base

undo "move HttpDateTime from android.webkit to android-common jar"

This restores this class to android.webkit, but leaves a copy in
android-common while I figure out how to move it correctly.

This reverts commit 7ad12a5f44253dc535f9a25ceb029579b40c43b1.

Change-Id: I1d0a3efe34764058b979c6987e6e774f64d02b8c