Underscore names are now forbidden

compiler/testData/codegen/box/classes/kt508.kt

@@ -4,9 +4,9 @@ public open class Identifier() {
     private var myNullable : Boolean = true
     companion object {
         open public fun init(isNullable : Boolean) : Identifier {
-            val __ = Identifier()
-            __.myNullable = isNullable
-            return __
+            val id = Identifier()
+            id.myNullable = isNullable
+            return id
         }
     }
 }

compiler/testData/codegen/box/objects/kt535.kt

@@ -5,8 +5,8 @@ class Identifier<T>(t : T?, myHasDollar : Boolean) {
 
     companion object {
         open public fun <T> init(name : T?) : Identifier<T> {
-            val __ = Identifier<T>(name, false)
-            return __
+            val id = Identifier<T>(name, false)
+            return id
         }
     }
     init {