Provide a fast path for MultiChildRenderObjectWrapper.syncRenderObject() when the children lists are identical.
Provide a fast path for MultiChildRenderObjectWrapper.syncRenderObject() when the children lists are identical.

This isn't so much for performance so much as because I don't want to
have to keep checking that the main syncChildren() function maintains
the invariant of not screwing up when the two lists are actually the
same list.

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