Backport from Linker: ElimStaticThis: allow more calls to static methods

Before there was an implicit assumption that static methods are only
present on objects.
This assumption is invalidated both by linker optimizations and the new
fix to lambdalift.

Author: DarkDimius

src/dotty/tools/dotc/transform/ElimStaticThis.scala

@@ -27,9 +27,11 @@ class ElimStaticThis extends MiniPhaseTransform {
   override def transformIdent(tree: tpd.Ident)(implicit ctx: Context, info: TransformerInfo): tpd.Tree = {
     if (ctx.owner.enclosingMethod.is(JavaStatic)) {
       tree.tpe match {
-        case TermRef(thiz: ThisType, _) =>
-          assert(thiz.underlying.typeSymbol.is(ModuleClass))
+        case TermRef(thiz: ThisType, _) if thiz.underlying.typeSymbol.is(ModuleClass) =>
           ref(thiz.underlying.typeSymbol.sourceModule).select(tree.symbol)
+        case TermRef(thiz: ThisType, _) =>
+          assert(tree.symbol.is(Flags.JavaStatic))
+          tree
         case _ => tree
       }
     }