* Return inserted/replaced paths
This gives `Path`’s replacement and insertion methods a consistent
return value: the inserted/replaced paths.
Before, they could return `undefined`, a `node`, or a the current path
inside an array. It was kinda pointless. But now they always return an
array of paths, which is useful for solving
https://github.com/babel/babel/pull/4935#discussion_r96151368.
* Return inserted nodes and not BlockStatement
Addded test for bug #4363
* Cleanups
- `#replaceWith` will now return the current path if it's the same node
- `#insertAfter` and `#insertBefore` use public Path APIs now
- Makes container insertion faster (single splice call)
- Use public APIs in container insertion
- Replacing a statement with an expression returns the expression's path
- Replacing an expression with multiple statements returns the inserted
closure's body's paths.
4daf11528c