libtxt: better accuracy for text justification (#4255)
libtxt: better accuracy for text justification (#4255)

* do not reset the justify offset after each run within a line
* track word start/end ranges relative to the start of the text instead of the line
krisgiesing/sky_engine,mikejurka/engine,jason-simmons/flutter_engine,tvolkert/engine,mikejurka/engine,krisgiesing/sky_engine,cdotstout/sky_engine,jason-simmons/sky_engine,chinmaygarde/sky_engine,jamesr/flutter_engine,devoncarew/sky_engine,aam/engine,jason-simmons/sky_engine,cdotstout/sky_engine,aam/engine,rmacnak-google/engine,Hixie/sky_engine,devoncarew/sky_engine,jamesr/sky_engine,jamesr/flutter_engine,jamesr/flutter_engine,jamesr/sky_engine,chinmaygarde/flutter_engine,mikejurka/engine,jason-simmons/flutter_engine,jamesr/sky_engine,jason-simmons/sky_engine,krisgiesing/sky_engine,rmacnak-google/engine,jamesr/flutter_engine,jason-simmons/flutter_engine,cdotstout/sky_engine,tvolkert/engine,jamesr/flutter_engine,chinmaygarde/flutter_engine,chinmaygarde/flutter_engine,devoncarew/engine,jason-simmons/flutter_engine,Hixie/sky_engine,jason-simmons/flutter_engine,chinmaygarde/flutter_engine,Hixie/sky_engine,tvolkert/engine,mikejurka/engine,jason-simmons/flutter_engine,jamesr/flutter_engine,jamesr/sky_engine,aam/engine,rmacnak-google/engine,chinmaygarde/sky_engine,chinmaygarde/sky_engine,cdotstout/sky_engine,tvolkert/engine,aam/engine,devoncarew/sky_engine,krisgiesing/sky_engine,jamesr/sky_engine,cdotstout/sky_engine,devoncarew/engine,devoncarew/sky_engine,cdotstout/sky_engine,flutter/engine,krisgiesing/sky_engine,cdotstout/sky_engine,devoncarew/engine,Hixie/sky_engine,jamesr/sky_engine,jamesr/flutter_engine,chinmaygarde/flutter_engine,devoncarew/sky_engine,jamesr/flutter_engine,devoncarew/sky_engine,rmacnak-google/engine,chinmaygarde/sky_engine,mikejurka/engine,Hixie/sky_engine,mikejurka/engine,krisgiesing/sky_engine,jason-simmons/flutter_engine,devoncarew/engine,chinmaygarde/flutter_engine,devoncarew/engine,Hixie/sky_engine,devoncarew/engine,flutter/engine,tvolkert/engine,mikejurka/engine,chinmaygarde/sky_engine,rmacnak-google/engine,tvolkert/engine,jason-simmons/sky_engine,jamesr/sky_engine,flutter/engine,chinmaygarde/flutter_engine,flutter/engine,aam/engine,jason-simmons/sky_engine,rmacnak-google/engine,aam/engine,mikejurka/engine,krisgiesing/sky_engine,devoncarew/engine,flutter/engine,rmacnak-google/engine,jason-simmons/sky_engine,jamesr/flutter_engine,devoncarew/sky_engine,flutter/engine,aam/engine,chinmaygarde/sky_engine,Hixie/sky_engine,mikejurka/engine,Hixie/sky_engine,tvolkert/engine,aam/engine,flutter/engine,jason-simmons/flutter_engine,jason-simmons/sky_engine,chinmaygarde/sky_engine,flutter/engine