Fix and simplify initializer

Initializer was needlessly complex and did not work anymore
for lazy vals (for them, we implicitly made use of the fact that
the initializer would find the symbol itself. But after name
mangling that logic would break down.

Author: odersky

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

@@ -112,17 +112,19 @@ class Mixin extends MiniPhaseTransform with SymTransformer { thisTransform =>
       sym
 
   private def initializer(sym: Symbol)(implicit ctx: Context): TermSymbol = {
-    val initName = if(!sym.is(Lazy)) InitializerName(sym.name.asTermName) else sym.name.asTermName
-    sym.owner.info.decl(initName).suchThat(_.is(Lazy) == sym.is(Lazy)).symbol
-      .orElse(
-        ctx.newSymbol(
-          sym.owner,
-          initName,
-          Protected | Synthetic | Method,
-          sym.info,
-          coord = sym.symbol.coord).enteredAfter(thisTransform))
-       .asTerm
-  }
+    if (sym is Lazy) sym
+    else {
+      val initName = InitializerName(sym.name.asTermName)
+      sym.owner.info.decl(initName).symbol
+        .orElse(
+          ctx.newSymbol(
+            sym.owner,
+            initName,
+            Protected | Synthetic | Method,
+            sym.info,
+            coord = sym.symbol.coord).enteredAfter(thisTransform))
+    }
+  }.asTerm
 
   override def transformTemplate(impl: Template)(implicit ctx: Context, info: TransformerInfo) = {
     val cls = impl.symbol.owner.asClass