Add a script to sky pub package to download assets
Add a script to sky pub package to download assets

This is a fork of sky/tools/download_material_design_assets
which does not depend on depot_tools and assumes that its
right next to the assets directory instead of finding it
relative to the mojo root.

R=ianh@google.com

Review URL: https://codereview.chromium.org/1106373002

chinmaygarde/flutter_engine,mdakin/engine,devoncarew/sky_engine,takaaptech/sky_engine,jamesr/sky_engine,jamesr/flutter_engine,takaaptech/sky_engine,afandria/sky_engine,chinmaygarde/sky_engine,TribeMedia/sky_engine,lyceel/engine,jason-simmons/flutter_engine,mpcomplete/engine,mikejurka/engine,chinmaygarde/flutter_engine,aam/engine,mpcomplete/engine,takaaptech/sky_engine,jason-simmons/flutter_engine,jamesr/flutter_engine,lyceel/engine,afandria/sky_engine,mdakin/engine,aam/engine,cdotstout/sky_engine,mpcomplete/flutter_engine,devoncarew/engine,rmacnak-google/engine,krisgiesing/sky_engine,afandria/sky_engine,devoncarew/engine,mikejurka/engine,krisgiesing/sky_engine,mpcomplete/flutter_engine,mdakin/engine,devoncarew/engine,iansf/sky_engine,abarth/sky_engine,lyceel/engine,jimsimon/sky_engine,rmacnak-google/engine,jamesr/sky_engine,axinging/sky_engine,axinging/sky_engine,jason-simmons/sky_engine,xunmengfeng/engine,jason-simmons/flutter_engine,axinging/sky_engine,mxia/engine,rmacnak-google/engine,cdotstout/sky_engine,axinging/sky_engine,takaaptech/sky_engine,qiankunshe/sky_engine,mikejurka/engine,jimsimon/sky_engine,abarth/sky_engine,qiankunshe/sky_engine,mdakin/engine,takaaptech/sky_engine,qiankunshe/sky_engine,mpcomplete/engine,jason-simmons/sky_engine,TribeMedia/sky_engine,flutter/engine,tvolkert/engine,mikejurka/engine,chinmaygarde/sky_engine,krisgiesing/sky_engine,chinmaygarde/sky_engine,jamesr/flutter_engine,Hixie/sky_engine,iansf/sky_engine,tvolkert/engine,axinging/sky_engine,afandria/sky_engine,mxia/engine,mdakin/engine,iansf/sky_engine,Hixie/sky_engine,mikejurka/engine,rmacnak-google/engine,lyceel/engine,xunmengfeng/engine,chinmaygarde/sky_engine,cdotstout/sky_engine,chinmaygarde/flutter_engine,devoncarew/engine,devoncarew/sky_engine,afandria/sky_engine,jason-simmons/sky_engine,flutter/engine,jason-simmons/sky_engine,qiankunshe/sky_engine,zhangxq5012/sky_engine,zhangxq5012/sky_engine,chinmaygarde/flutter_engine,devoncarew/engine,flutter/engine,jamesr/sky_engine,cdotstout/sky_engine,mpcomplete/engine,zhangxq5012/sky_engine,mxia/engine,chinmaygarde/sky_engine,aam/engine,abarth/sky_engine,mpcomplete/flutter_engine,chinmaygarde/sky_engine,cdotstout/sky_engine,krisgiesing/sky_engine,devoncarew/sky_engine,tvolkert/engine,mxia/engine,jason-simmons/flutter_engine,qiankunshe/sky_engine,TribeMedia/sky_engine,qiankunshe/sky_engine,jamesr/flutter_engine,devoncarew/engine,takaaptech/sky_engine,mdakin/engine,mpcomplete/flutter_engine,flutter/engine,iansf/sky_engine,takaaptech/sky_engine,iansf/sky_engine,jamesr/flutter_engine,chinmaygarde/flutter_engine,mpcomplete/engine,krisgiesing/sky_engine,mikejurka/engine,takaaptech/sky_engine,jimsimon/sky_engine,jason-simmons/flutter_engine,axinging/sky_engine,mxia/engine,jamesr/sky_engine,aam/engine,rmacnak-google/engine,iansf/sky_engine,cdotstout/sky_engine,afandria/sky_engine,axinging/sky_engine,abarth/sky_engine,mikejurka/engine,TribeMedia/sky_engine,devoncarew/sky_engine,Hixie/sky_engine,mxia/engine,Hixie/sky_engine,lyceel/engine,TribeMedia/sky_engine,lyceel/engine,tvolkert/engine,krisgiesing/sky_engine,TribeMedia/sky_engine,Hixie/sky_engine,jamesr/flutter_engine,jimsimon/sky_engine,mdakin/engine,qiankunshe/sky_engine,devoncarew/engine,mpcomplete/flutter_engine,flutter/engine,mdakin/engine,zhangxq5012/sky_engine,xunmengfeng/engine,jamesr/flutter_engine,jamesr/sky_engine,jason-simmons/sky_engine,flutter/engine,mikejurka/engine,flutter/engine,xunmengfeng/engine,abarth/sky_engine,mxia/engine,zhangxq5012/sky_engine,jimsimon/sky_engine,jason-simmons/flutter_engine,aam/engine,mpcomplete/engine,jimsimon/sky_engine,Hixie/sky_engine,zhangxq5012/sky_engine,jimsimon/sky_engine,axinging/sky_engine,iansf/sky_engine,tvolkert/engine,Hixie/sky_engine,mxia/engine,jason-simmons/flutter_engine,jason-simmons/sky_engine,chinmaygarde/flutter_engine,mpcomplete/flutter_engine,takaaptech/sky_engine,lyceel/engine,jamesr/sky_engine,TribeMedia/sky_engine,chinmaygarde/flutter_engine,jason-simmons/sky_engine,afandria/sky_engine,aam/engine,krisgiesing/sky_engine,qiankunshe/sky_engine,jason-simmons/flutter_engine,rmacnak-google/engine,xunmengfeng/engine,tvolkert/engine,iansf/sky_engine,xunmengfeng/engine,flutter/engine,tvolkert/engine,jamesr/flutter_engine,zhangxq5012/sky_engine,axinging/sky_engine,mikejurka/engine,zhangxq5012/sky_engine,devoncarew/sky_engine,Hixie/sky_engine,mpcomplete/engine,jamesr/flutter_engine,devoncarew/sky_engine,rmacnak-google/engine,aam/engine,abarth/sky_engine,xunmengfeng/engine,jimsimon/sky_engine,chinmaygarde/sky_engine,abarth/sky_engine,devoncarew/sky_engine,TribeMedia/sky_engine,mpcomplete/engine,TribeMedia/sky_engine,aam/engine,afandria/sky_engine,jimsimon/sky_engine,cdotstout/sky_engine,zhangxq5012/sky_engine,jamesr/sky_engine