Fix #2437: Drop erroneous case ib Pickler

The case was a left-over from when we did not pickle
types as trees. There was a special case to record the symbol
of a bound type variable. This is no longer needed as we now
pickle the full tree that defines the symbol.

Author: odersky

compiler/src/dotty/tools/dotc/core/tasty/TreePickler.scala

@@ -148,32 +148,21 @@ class TreePickler(pickler: TastyPickler) {
       pickleType(tpe.superType)
     case tpe: WithFixedSym =>
       val sym = tpe.symbol
-      def pickleRef() =
-        if (tpe.prefix == NoPrefix) {
-          writeByte(if (tpe.isType) TYPEREFdirect else TERMREFdirect)
-          pickleSymRef(sym)
-        }
-        else {
-          assert(tpe.symbol.isClass)
-          assert(tpe.symbol.is(Flags.Scala2x), tpe.symbol.showLocated)
-          writeByte(TYPEREF) // should be changed to a new entry that keeps track of prefix, symbol & owner
-          pickleName(tpe.name)
-          pickleType(tpe.prefix)
-        }
       if (sym.is(Flags.Package)) {
         writeByte(if (tpe.isType) TYPEREFpkg else TERMREFpkg)
         pickleName(sym.fullName)
       }
-      else if (sym is Flags.BindDefinedType) {
-        registerDef(sym)
-        writeByte(BIND)
-        withLength {
-          pickleName(sym.name)
-          pickleType(sym.info)
-          pickleRef()
-        }
+      else if (tpe.prefix == NoPrefix) {
+        writeByte(if (tpe.isType) TYPEREFdirect else TERMREFdirect)
+        pickleSymRef(sym)
+      }
+      else {
+        assert(tpe.symbol.isClass)
+        assert(tpe.symbol.is(Flags.Scala2x), tpe.symbol.showLocated)
+        writeByte(TYPEREF) // should be changed to a new entry that keeps track of prefix, symbol & owner
+        pickleName(tpe.name)
+        pickleType(tpe.prefix)
       }
-      else pickleRef()
     case tpe: TermRefWithSignature =>
       if (tpe.symbol.is(Flags.Package)) picklePackageRef(tpe.symbol)
       else {