(Un)mute and add tests for vararg codegen

compiler/testData/codegen/bytecodeText/inlineClasses/passInlineClassesWithSpreadOperatorToVarargs.kt

@@ -9,7 +9,7 @@ inline class UInt(val u: Int)
 fun <T> takeVarargs(vararg e: T) {}
 
 fun test(u1: UInt, u2: UInt, us: Array<UInt>) {
-    takeVarargs(*us) // copy + checkcast
+    takeVarargs(*us) // copy + checkcast (on non-ir backend)
     takeVarargs(u1, u2, *us) // 2 box + ...
 }
 
@@ -17,9 +17,13 @@ fun test(u1: UInt, u2: UInt, us: Array<UInt>) {
 // 2 INVOKESTATIC UInt\.box
 // 0 INVOKEVIRTUAL UInt.unbox
 
-// 2 CHECKCAST \[LUInt
-
 // 0 CHECKCAST \[Ljava/lang/Integer
 
 // 0 intValue
-// 0 valueOf
+// 0 valueOf
+
+// JVM_TEMPLATES
+// 2 CHECKCAST \[LUInt
+
+// JVM_IR_TEMPLATES
+// 1 CHECKCAST \[LUInt