Add a default BoxDecorationPosition
Add a default BoxDecorationPosition

Fixes the tests because previously we wouldn't draw any box decorations.

cbracken/flutter,tvolkert/flutter,cbracken/flutter,tvolkert/flutter,tvolkert/flutter,Hixie/flutter,cbracken/flutter,turnidge/flutter,cbracken/flutter,flutter/flutter,turnidge/flutter,flutter/flutter,jason-simmons/flutter,cbracken/flutter,Hixie/flutter,tvolkert/flutter,aghassemi/flutter,cbracken/flutter,Hixie/flutter,Hixie/flutter,jason-simmons/flutter,flutter/flutter,cbracken/flutter,jason-simmons/flutter,cbracken/flutter,turnidge/flutter,flutter/flutter,flutter/flutter,cbracken/flutter,Hixie/flutter,flutter/flutter,tvolkert/flutter,tvolkert/flutter,flutter/flutter,turnidge/flutter,aghassemi/flutter,tvolkert/flutter,tvolkert/flutter,tvolkert/flutter,Hixie/flutter,Hixie/flutter,Hixie/flutter,cbracken/flutter,turnidge/flutter,Hixie/flutter,tvolkert/flutter,aghassemi/flutter,jason-simmons/flutter,flutter/flutter,Hixie/flutter,flutter/flutter,aghassemi/flutter,flutter/flutter