Advanced Loading Control

The loader API now provides a new LoadingContext object, which provides new features:

• importer provides the resolved path of the parent sourcemap.
• source allows the loader to change the resolved location of the transformed sourcemap or original source file.
• content allows override the parent sourcemap's sourcesContent field for an original source file.

See https://github.com/ampproject/remapping#advanced-control-of-the-loading-graph for more information.