Fix test syntax

Author: som-snytt

tests/neg/i22527.scala

@@ -23,3 +23,8 @@ def g: Unit =
       class X extends AnyRef, Serializable // error
       27 // error
   )
+
+def onlyIf(x: Int): Unit =
+  callme(
+    if (x > 0)
+      true, "fail") // error syntax is broken after old-style conditional

tests/pos/i22527.scala

@@ -41,7 +41,7 @@ def orElse(x: Int): Unit =
 @nowarn("msg=Unit")
 def onlyIf(x: Int): Unit =
   callme(
-    if (x > 0)
+    if (x > 0) then // then syntax required
       true, "fail") // warn value discard
 
 def h(xs: List[Int]) =

tests/warn/i22527.scala

@@ -36,7 +36,7 @@ def orElse(x: Int): Unit =
 
 def onlyIf(x: Int): Unit =
   callme(
-    if (x > 0)
+    if x > 0 then
       true, "fail") // warn value discard
 
 def h(xs: List[Int]) =