In GJS, jasmineGlobal was not getting set to the global object; when
importing jasmine.js in GJS, "this" resolves to the jasmine.js module
object, not the global object. Solve this specifically for GJS by
assuming that `window.toString === '[object GjsGlobal]'` only in GJS; if
this is the case, assign "window" to "jasmineGlobal".
Adding a "var" to the declaration of "getJasmineRequireObj" is also
necessary, or else "getJasmineRequireObj" won't be exported in the
Jasmine module.
See #751
ebaa2e7f24