Summary:
Many RN devtools (inspector, source maps, etc.) rely on packager.
This refactors individual SourceCode.scriptURL parsing into one function
that will be easier to change in the future.
Reviewed By: javache
Differential Revision: D3348465
fbshipit-source-id: 5a55939ea59e1517cb63bcbe4963f57f02ab15f3
Alex Kotliarskyi