Adaptations needed for new classOf handling.

Previously, the implicit definitions were always ambiguous, which
is surely not right.

Author: odersky

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

@@ -179,14 +179,14 @@ class DottyBackendInterface(outputDirectory: AbstractFile)(implicit ctx: Context
   implicit val ApplyTag: ClassTag[Apply] = ClassTag[Apply](classOf[Apply])
   implicit val SelectTag: ClassTag[Select] = ClassTag[Select](classOf[Select])
   implicit val TypeApplyTag: ClassTag[TypeApply] = ClassTag[TypeApply](classOf[TypeApply])
-  implicit val ClassDefTag: ClassTag[ClassDef] = ClassTag[TypeDef](classOf[TypeDef])
+           val ClassDefTag: ClassTag[ClassDef] = ClassTag[TypeDef](classOf[TypeDef]) // no implicit, it's an alias of TypeDefTag
   implicit val TryTag: ClassTag[Try] = ClassTag[Try](classOf[Try])
   implicit val AssignTag: ClassTag[Assign] = ClassTag[Assign](classOf[Assign])
   implicit val IdentTag: ClassTag[Ident] = ClassTag[Ident](classOf[Ident])
   implicit val IfTag: ClassTag[If] = ClassTag[If](classOf[If])
-  implicit val LabelDefTag: ClassTag[LabelDef] = ClassTag[LabelDef](classOf[LabelDef])
+           val LabelDefTag: ClassTag[LabelDef] = ClassTag[LabelDef](classOf[LabelDef]) // no implicit, it's an alias of DefDefTag
   implicit val ValDefTag: ClassTag[ValDef] = ClassTag[ValDef](classOf[ValDef])
-  implicit val ThrowTag: ClassTag[Throw] = ClassTag[Throw](classOf[Throw])
+           val ThrowTag: ClassTag[Throw] = ClassTag[Throw](classOf[Throw]) // no implicit, it's an alias of ApplyTag
   implicit val ReturnTag: ClassTag[Return] = ClassTag[Return](classOf[Return])
   implicit val LiteralTag: ClassTag[Literal] = ClassTag[Literal](classOf[Literal])
   implicit val BlockTag: ClassTag[Block] = ClassTag[Block](classOf[Block])
@@ -197,12 +197,12 @@ class DottyBackendInterface(outputDirectory: AbstractFile)(implicit ctx: Context
   implicit val ThisTag: ClassTag[This] = ClassTag[This](classOf[This])
   implicit val AlternativeTag: ClassTag[Alternative] = ClassTag[Alternative](classOf[Alternative])
   implicit val DefDefTag: ClassTag[DefDef] = ClassTag[DefDef](classOf[DefDef])
-  implicit val ModuleDefTag: ClassTag[ModuleDef] = ClassTag[ModuleDef](classOf[ModuleDef])
+           val ModuleDefTag: ClassTag[ModuleDef] = ClassTag[ModuleDef](classOf[ModuleDef]) // no implicit, it's an alias of NullTag
   implicit val NameTag: ClassTag[Name] = ClassTag[Name](classOf[Name])
   implicit val TemplateTag: ClassTag[Template] = ClassTag[Template](classOf[Template])
   implicit val BindTag: ClassTag[Bind] = ClassTag[Bind](classOf[Bind])
   implicit val NewTag: ClassTag[New] = ClassTag[New](classOf[New])
-  implicit val ApplyDynamicTag: ClassTag[ApplyDynamic] = ClassTag[ApplyDynamic](classOf[ApplyDynamic])
+           val ApplyDynamicTag: ClassTag[ApplyDynamic] = ClassTag[ApplyDynamic](classOf[ApplyDynamic]) // no implicit, it's an alias of NullTag
   implicit val SuperTag: ClassTag[Super] = ClassTag[Super](classOf[Super])
   implicit val ConstantClassTag: ClassTag[Constant] = ClassTag[Constant](classOf[Constant])
   implicit val ClosureTag: ClassTag[Closure] = ClassTag[Closure](classOf[Closure])