Remove unnecessary changes done to scalac

Author: felixmulder

compiler/src/dotty/tools/backend/jvm/DottyBackendInterface.scala

@@ -11,7 +11,7 @@ import java.io.{File => JFile}
 import scala.collection.generic.Clearable
 import scala.collection.mutable
 import scala.reflect.ClassTag
-import scala.tools.nsc.util.WeakHashSet
+import scala.reflect.internal.util.WeakHashSet
 import dotty.tools.io.{AbstractFile, Directory, PlainDirectory}
 import scala.tools.asm.{AnnotationVisitor, ClassVisitor, FieldVisitor, MethodVisitor}
 import scala.tools.nsc.backend.jvm.{BCodeHelpers, BackendInterface}

compiler/src/scala/reflect/internal/pickling/package.scala

@@ -0,0 +1,6 @@
+package scala.reflect.internal
+
+package object pickling {
+  type PickleBuffer = dotty.tools.dotc.core.unpickleScala2.PickleBuffer
+  val PickleFormat = dotty.tools.dotc.core.unpickleScala2.PickleFormat
+}

compiler/src/scala/reflect/internal/util/package.scala

@@ -0,0 +1,5 @@
+package scala.reflect.internal
+
+package object util {
+  type WeakHashSet[T >: Null <: AnyRef] = dotty.tools.dotc.util.WeakHashSet[T]
+}