Make 'changed' faster by not instantiating already injected targets
Make 'changed' faster by not instantiating already injected targets

Testing Done:
Travis passed. https://travis-ci.org/pantsbuild/pants/builds/85231805

Bugs closed: 2368

Reviewed at https://rbcommons.com/s/twitter/r/2967/

mateor/pants,UnrememberMe/pants,pombredanne/pants,lahosken/pants,megaserg/pants,ericzundel/pants,foursquare/pants,twitter/pants,kwlzn/pants,qma/pants,15Dkatz/pants,manasapte/pants,fkorotkov/pants,peiyuwang/pants,qma/pants,tdyas/pants,jtrobec/pants,jessrosenfield/pants,ericzundel/pants,peiyuwang/pants,gmalmquist/pants,UnrememberMe/pants,ity/pants,qma/pants,15Dkatz/pants,qma/pants,benjyw/pants,ity/pants,pantsbuild/pants,kwlzn/pants,15Dkatz/pants,dbentley/pants,baroquebobcat/pants,foursquare/pants,gmalmquist/pants,UnrememberMe/pants,mateor/pants,benjyw/pants,gmalmquist/pants,peiyuwang/pants,cevaris/pants,dbentley/pants,wisechengyi/pants,pantsbuild/pants,pombredanne/pants,UnrememberMe/pants,fkorotkov/pants,megaserg/pants,baroquebobcat/pants,lahosken/pants,baroquebobcat/pants,mateor/pants,peiyuwang/pants,megaserg/pants,benjyw/pants,kwlzn/pants,lahosken/pants,peiyuwang/pants,pombredanne/pants,lahosken/pants,fkorotkov/pants,gmalmquist/pants,15Dkatz/pants,baroquebobcat/pants,fkorotkov/pants,jtrobec/pants,cevaris/pants,pantsbuild/pants,foursquare/pants,jsirois/pants,jessrosenfield/pants,wisechengyi/pants,tdyas/pants,landism/pants,landism/pants,twitter/pants,tdyas/pants,jessrosenfield/pants,UnrememberMe/pants,pantsbuild/pants,wisechengyi/pants,15Dkatz/pants,ity/pants,twitter/pants,foursquare/pants,qma/pants,lahosken/pants,dbentley/pants,landism/pants,jtrobec/pants,baroquebobcat/pants,wisechengyi/pants,megaserg/pants,wisechengyi/pants,manasapte/pants,landism/pants,foursquare/pants,cevaris/pants,manasapte/pants,baroquebobcat/pants,megaserg/pants,tdyas/pants,fkorotkov/pants,wisechengyi/pants,baroquebobcat/pants,dbentley/pants,dturner-tw/pants,landism/pants,foursquare/pants,lahosken/pants,dturner-tw/pants,cevaris/pants,lahosken/pants,fkorotkov/pants,ericzundel/pants,jessrosenfield/pants,ity/pants,cevaris/pants,fkorotkov/pants,jessrosenfield/pants,dturner-tw/pants,dturner-tw/pants,15Dkatz/pants,benjyw/pants,ericzundel/pants,twitter/pants,manasapte/pants,foursquare/pants,kwlzn/pants,ity/pants,foursquare/pants,baroquebobcat/pants,15Dkatz/pants,megaserg/pants,wisechengyi/pants,qma/pants,jtrobec/pants,dturner-tw/pants,landism/pants,wisechengyi/pants,dbentley/pants,mateor/pants,jsirois/pants,pantsbuild/pants,twitter/pants,landism/pants,gmalmquist/pants,baroquebobcat/pants,mateor/pants,ericzundel/pants,mateor/pants,jtrobec/pants,kwlzn/pants,twitter/pants,tdyas/pants,twitter/pants,15Dkatz/pants,pantsbuild/pants,dturner-tw/pants,peiyuwang/pants,dbentley/pants,ity/pants,ericzundel/pants,tdyas/pants,UnrememberMe/pants,manasapte/pants,pombredanne/pants,wisechengyi/pants,jtrobec/pants,UnrememberMe/pants,benjyw/pants,pombredanne/pants,jsirois/pants,ity/pants,qma/pants,lahosken/pants,cevaris/pants,ericzundel/pants,landism/pants,manasapte/pants,mateor/pants,tdyas/pants,megaserg/pants,manasapte/pants,UnrememberMe/pants,UnrememberMe/pants,benjyw/pants,jessrosenfield/pants,foursquare/pants,twitter/pants,cevaris/pants,gmalmquist/pants,pantsbuild/pants,pombredanne/pants,tdyas/pants,kwlzn/pants,dbentley/pants,jessrosenfield/pants,jtrobec/pants,gmalmquist/pants,peiyuwang/pants,benjyw/pants,twitter/pants,fkorotkov/pants,ericzundel/pants,peiyuwang/pants,pombredanne/pants,mateor/pants,kwlzn/pants,dturner-tw/pants,tdyas/pants