Anonymous define() function can break require.js JS apps

I have a requirejs based javascript app that's loaded inside of my Drupal site. In FF and Safari (but not Chrome), I'd get the following error:

Mismatched anonymous define() module: function () { "use strict"; return d; } http://requirejs.org/docs/errors.html#mismatch

It turned out to be the use of define in picturefill.js:

 if ( typeof define === "function" && define.amd ){
    // AMD support
    define( function() { return picturefill; } );
  }

This anonymous call to define() didn't play well with require.js, and in my case, it broke picture.js which was looking for a global object.