lerpDouble: add tests for NaN, infinity (#20848)
lerpDouble: add tests for NaN, infinity (#20848)

Adds tests for lerpDouble for cases where NaN or infinite values are
passed. These tests simply specify the current behaviour.
aam/engine,jamesr/flutter_engine,jamesr/sky_engine,flutter/engine,jamesr/flutter_engine,jason-simmons/flutter_engine,jason-simmons/flutter_engine,Hixie/sky_engine,flutter/engine,chinmaygarde/flutter_engine,flutter/engine,Hixie/sky_engine,chinmaygarde/flutter_engine,chinmaygarde/sky_engine,Hixie/sky_engine,devoncarew/sky_engine,jason-simmons/sky_engine,jason-simmons/sky_engine,devoncarew/engine,jason-simmons/flutter_engine,rmacnak-google/engine,aam/engine,chinmaygarde/flutter_engine,flutter/engine,jamesr/flutter_engine,jamesr/sky_engine,flutter/engine,aam/engine,devoncarew/sky_engine,chinmaygarde/flutter_engine,chinmaygarde/sky_engine,jamesr/sky_engine,jason-simmons/sky_engine,Hixie/sky_engine,rmacnak-google/engine,devoncarew/engine,aam/engine,jamesr/flutter_engine,flutter/engine,chinmaygarde/sky_engine,devoncarew/sky_engine,jamesr/flutter_engine,jason-simmons/sky_engine,chinmaygarde/flutter_engine,rmacnak-google/engine,devoncarew/sky_engine,flutter/engine,aam/engine,rmacnak-google/engine,devoncarew/engine,devoncarew/engine,jamesr/flutter_engine,jason-simmons/flutter_engine,jason-simmons/sky_engine,jason-simmons/flutter_engine,jason-simmons/sky_engine,aam/engine,jamesr/sky_engine,jason-simmons/sky_engine,chinmaygarde/sky_engine,chinmaygarde/flutter_engine,devoncarew/engine,devoncarew/sky_engine,jamesr/sky_engine,Hixie/sky_engine,chinmaygarde/sky_engine,rmacnak-google/engine,devoncarew/sky_engine,chinmaygarde/flutter_engine,jamesr/sky_engine,rmacnak-google/engine,Hixie/sky_engine,jamesr/flutter_engine,rmacnak-google/engine,devoncarew/sky_engine,flutter/engine,devoncarew/engine,jamesr/flutter_engine,Hixie/sky_engine,aam/engine,jason-simmons/flutter_engine,jamesr/flutter_engine,jason-simmons/flutter_engine,jamesr/sky_engine,Hixie/sky_engine,devoncarew/engine,chinmaygarde/sky_engine,chinmaygarde/sky_engine,aam/engine,jason-simmons/flutter_engine