Avoid unnecessary narrowLiftedOwner in markFree

This prevented many local functions from being lifted out
to static scope, and thereby caused memory leaks. The memory leak found
in the IDE was caused an anonymous function in NamerContextOps (a base
trait of Context) that was kept as a non-private private method of
NamerContextOps, taking a `this` referring to a context.

Author: odersky

compiler/src/dotty/tools/dotc/transform/LambdaLift.scala

@@ -204,7 +204,7 @@ class LambdaLift extends MiniPhase with IdentityDenotTransformer { thisTransform
           if (enclosure.is(PackageClass)) enclosure
           else if (enclosure.isConstructor) markFree(sym, enclosure.owner.enclosure)
           else markFree(sym, enclosure.enclosure)
-        narrowLiftedOwner(enclosure, intermediate orElse sym.enclosingClass)
+        if (intermediate.exists) narrowLiftedOwner(enclosure, intermediate)
         if (!intermediate.isRealClass || enclosure.isConstructor) {
           // Constructors and methods nested inside traits get the free variables
           // of the enclosing trait or class.
@@ -384,7 +384,7 @@ class LambdaLift extends MiniPhase with IdentityDenotTransformer { thisTransform
         local.copySymDenotation(
           owner = newOwner,
           name = newName(local),
-          initFlags = local.flags &~ Module | Private | maybeStatic,
+          initFlags = local.flags &~ Module &~ Final | Private | maybeStatic,
             // drop Module because class is no longer a singleton in the lifted context.
           info = liftedInfo(local)).installAfter(thisTransform)
       }