fix: globalScope is undefined when running in JSCore Environment

[smalldice]

Hello, An issue came when I use node-forge in JSCore environment, at lib/random.js line 119, globalScope returns undefined, cause globalScope.crypto throw Error "can't read property crypto of undefined", so I changed lib/util.js getScopeFunction to fix this problem

[ProgrammerHuang]

The same problem at prng.js line 271.