Compiler: use the reporter passed from the Driver

With this commit and the previous one, partest should finally correctly
log the output of the compiler and display it at the end of its
execution if compilation failed.

Author: smarter

src/dotty/tools/dotc/Compiler.scala

@@ -111,15 +111,13 @@ class Compiler {
       .setOwner(defn.RootClass)
       .setTyper(new Typer)
       .setMode(Mode.ImplicitsEnabled)
-      .setTyperState(new MutableTyperState(ctx.typerState, rootReporter(ctx), isCommittable = true))
+      .setTyperState(new MutableTyperState(ctx.typerState, ctx.typerState.reporter, isCommittable = true))
     ctx.definitions.init(start) // set context of definitions to start
     def addImport(ctx: Context, refFn: () => TermRef) =
       ctx.fresh.setImportInfo(ImportInfo.rootImport(refFn)(ctx))
     (start.setRunInfo(new RunInfo(start)) /: defn.RootImportFns)(addImport)
   }
 
-  protected def rootReporter(implicit ctx: Context): Reporter = new ConsoleReporter()
-
   def reset()(implicit ctx: Context): Unit = {
     ctx.base.reset()
     ctx.runInfo.clear()