Initialize MinikinPaint members
Initialize MinikinPaint members

We are stack-allocating MinikinPaint objects in Minikin clients, and
without a constructor adding new members to the struct cannot be done
without updating all clients (only one right now!).

Change-Id: I4170f16498bb6b07cb795495011aca58087ed0bd

aam/engine,Hixie/sky_engine,rmacnak-google/engine,aam/engine,jason-simmons/sky_engine,jamesr/flutter_engine,devoncarew/engine,mikejurka/engine,mikejurka/engine,krisgiesing/sky_engine,rmacnak-google/engine,cdotstout/sky_engine,tvolkert/engine,Hixie/sky_engine,tvolkert/engine,devoncarew/sky_engine,devoncarew/engine,devoncarew/sky_engine,flutter/engine,cdotstout/sky_engine,devoncarew/sky_engine,cdotstout/sky_engine,jamesr/sky_engine,devoncarew/engine,jason-simmons/flutter_engine,Hixie/sky_engine,chinmaygarde/flutter_engine,jason-simmons/flutter_engine,aam/engine,devoncarew/sky_engine,mikejurka/engine,chinmaygarde/sky_engine,aam/engine,jamesr/sky_engine,rmacnak-google/engine,aam/engine,devoncarew/engine,jason-simmons/sky_engine,aam/engine,krisgiesing/sky_engine,jamesr/sky_engine,chinmaygarde/flutter_engine,tvolkert/engine,krisgiesing/sky_engine,chinmaygarde/flutter_engine,jason-simmons/flutter_engine,rmacnak-google/engine,jason-simmons/sky_engine,flutter/engine,jason-simmons/flutter_engine,devoncarew/engine,jamesr/flutter_engine,chinmaygarde/flutter_engine,chinmaygarde/sky_engine,mikejurka/engine,chinmaygarde/sky_engine,jamesr/flutter_engine,devoncarew/sky_engine,krisgiesing/sky_engine,jason-simmons/sky_engine,jason-simmons/flutter_engine,jason-simmons/flutter_engine,jason-simmons/sky_engine,jamesr/flutter_engine,aam/engine,jamesr/flutter_engine,jamesr/flutter_engine,Hixie/sky_engine,jamesr/flutter_engine,jason-simmons/flutter_engine,mikejurka/engine,krisgiesing/sky_engine,devoncarew/engine,jamesr/sky_engine,jason-simmons/flutter_engine,tvolkert/engine,cdotstout/sky_engine,cdotstout/sky_engine,jamesr/sky_engine,chinmaygarde/sky_engine,Hixie/sky_engine,chinmaygarde/flutter_engine,chinmaygarde/sky_engine,flutter/engine,devoncarew/sky_engine,mikejurka/engine,cdotstout/sky_engine,krisgiesing/sky_engine,rmacnak-google/engine,aam/engine,flutter/engine,chinmaygarde/sky_engine,chinmaygarde/sky_engine,chinmaygarde/flutter_engine,tvolkert/engine,mikejurka/engine,jamesr/flutter_engine,jamesr/sky_engine,rmacnak-google/engine,cdotstout/sky_engine,Hixie/sky_engine,tvolkert/engine,mikejurka/engine,jason-simmons/sky_engine,devoncarew/sky_engine,Hixie/sky_engine,flutter/engine,flutter/engine,jamesr/flutter_engine,Hixie/sky_engine,flutter/engine,devoncarew/engine,jason-simmons/sky_engine,chinmaygarde/flutter_engine,krisgiesing/sky_engine,rmacnak-google/engine,jamesr/sky_engine,tvolkert/engine,flutter/engine,mikejurka/engine