Revert "Remove the classic WebView from the build."

This reverts commit 3e9cdbe3fe00ef50eff256e7b5f4b6a1ae796ec5.

Change-Id: If0755d3e9b2846827e6e8b773ffe45f772c30275
Revert "Revert "Support a prebuilt WebView.""

This reverts commit a52bf0f6b156d329231509364d303c4102057239.