Javascript interpreter change? Yang?

I'm researching a problem we have since being upgraded.  I'm getting ReferenceError errors and I think it may have to do with a Script that has a reference to an object that is undefined.

For example:
Script Record "A"
Script File: fileA.js
Library File: Library.js

Script Record "B"
Script File: FileA.js
Library File: PricingMgr.js
Library File: Library.js

FileA.js contents:

 function foo()  {      // do stuff, great, fine  }    function methodThatNeedsObjectsDefinedInPricingMgrFile()  {      //  The following object is defined in PricingMgr.js      var priceMgr = new PricingMgr();  } 

Now, ScriptA never invokes methodThatNeedsObjectsDefinedInPricingMgrFile but ScriptB does and that's why it has the PricingMgr.js file included.