LayoutLib: fix XmlUtils.convertValueToInt

It looks like the device implementation of Integer.parseInt
is able to handle converting hexa value > 80000000 while the
desktop VM cannot.

This patch provide a fix for this.

While implementing it and running the TestDegates test I realized
that some delegate methods for Region were mising, so this adds them
too.

Change-Id: Ifee1efd47c8c52adc2f4658ec4fc8bd55adb84b4