Fix for IE7 spec failure when run against knockout-raw.js
Fix for IE7 spec failure when run against knockout-raw.js

For some reason, on IE7 json2.js is treated as not yet loaded when
knockout-raw.js first starts running, even though its script tag is
higher up in the page. So it doesn’t work to capture a reference to it
in the test. However this doesn’t affect production builds.

brianmhunt/knockout,cgourlay/knockout,skyh/knockout,getshuvo/knockout,martijnwetering/knockout,xeronith/knockout,skyh/knockout,moonpyk/knockout,DekeYan/knockout,bago/knockout,stonegithubs/knockout,brianmhunt/knockout,bago/knockout,ErikSchierboom/knockout,martijnwetering/knockout,mattbalmer/knuckles,gwokudasam/knockout,pianove/knockout,gwokudasam/knockout,pianove/knockout,youprofit/knockout,mattbalmer/knuckles,Sir0xb/knockout,moonpyk/knockout,xeronith/knockout,hitesh97/knockout,hitesh97/knockout,ErikSchierboom/knockout,JesseQin/knockout,stonegithubs/knockout,JesseQin/knockout,DekeYan/knockout,youprofit/knockout,cgourlay/knockout,Sir0xb/knockout,getshuvo/knockout