(Un)mute and add tests for vararg codegen

compiler/testData/codegen/bytecodeText/defaultArguments/noEmptyArray.kt

@@ -1,5 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
-
 // There is one ANEWARRAY instruction here, to generate the default parameter value.
 fun default(vararg s: String = arrayOf("OK")) = s[0]
 

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

compiler/testData/codegen/bytecodeText/varargs/doNotCopyImmediatelyCreatedArrays.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND: JVM_IR
 fun booleanVararg(vararg xs: Boolean) {}
 fun byteVararg(vararg xs: Byte) {}
 fun shortVararg(vararg xs: Short) {}
@@ -74,5 +73,6 @@ fun test() {
     genericVararg(xs = *arrayOfNulls<Int>(1))
 }
 
+// 0 arraycopy
 // 0 copyOf
 // 0 clone