REPL: Import shadowing issue

[allanrenucci]

scala> object A { def f = 1 }                                                                                                                                                                                   
// defined object A

scala> import A._; def f = 2
def f: Int

scala> f                                                                                                                                                                                                        
val res0: Int = 1 // should be 2

[allanrenucci]

This has to do with the way we handle user defined imports and wrap expression in an object:

When we evaluate an expression, we need to imports previously evaluated expressions:
https://github.com/lampepfl/dotty/blob/86c4e72e3a87aae12c57e2c887231b77717438a3/compiler/src/dotty/tools/repl/ReplCompiler.scala#L50-L66

We first import the wrapper object and then the user defined imports in it. So a user defined import might shadow a definition even if the import precedes the definition