Summary of changes:

This used to be  `class Eraser(_context: Context) extends Typer(_context)`,
where `typedPos(tree.pos)(tree1)` has become `typer2.typedPos(tree.pos)(tree1)`

// one new member:
`private def isErasedValueType(tpe: Type) = tpe.isInstanceOf[ErasedValueType]`

// following members no longer private:
```
def isPrimitiveValueMember(sym: Symbol) = isPrimitiveValueClass(sym.owner)
def box(tree: Tree, target: => String): Tree = {
def unbox(tree: Tree, pt: Type): Tree = {
def cast(tree: Tree, pt: Type): Tree = {
def adaptToType(tree: Tree, pt: Type): Tree = {
def isMethodTypeWithEmptyParams(tpe: Type) = tpe match {
```