WASM: Implement spread operator

compiler/testData/codegen/box/vararg/doNotCopyImmediatelyCreatedArrays.kt

@@ -1,5 +1,3 @@
-// DONT_TARGET_EXACT_BACKEND: WASM
-// WASM_MUTE_REASON: SPREAD_OPERATOR
 fun booleanVararg(vararg xs: Boolean) {
     if (xs.size != 1 && xs[0] != true) throw AssertionError()
 }

compiler/testData/codegen/box/vararg/kt37779.kt

@@ -1,5 +1,3 @@
-// DONT_TARGET_EXACT_BACKEND: WASM
-// WASM_MUTE_REASON: SPREAD_OPERATOR
 // !LANGUAGE: +AllowAssigningArrayElementsToVarargsInNamedFormForFunctions
 
 fun test(vararg s: String) = s[1] + s.size

compiler/testData/codegen/box/vararg/kt6192.kt

@@ -1,5 +1,3 @@
-// DONT_TARGET_EXACT_BACKEND: WASM
-// WASM_MUTE_REASON: SPREAD_OPERATOR
 fun barB(vararg args: Byte) = args
 fun barC(vararg args: Char) = args
 fun barD(vararg args: Double) = args

compiler/testData/codegen/box/vararg/spreadCopiesArray.kt

@@ -1,5 +1,3 @@
-// DONT_TARGET_EXACT_BACKEND: WASM
-// WASM_MUTE_REASON: SPREAD_OPERATOR
 // WITH_RUNTIME
 
 import kotlin.test.*

compiler/testData/codegen/box/vararg/varargInFunParam.kt

@@ -1,5 +1,3 @@
-// DONT_TARGET_EXACT_BACKEND: WASM
-// WASM_MUTE_REASON: SPREAD_OPERATOR
 fun box(): String {
     if (test1() != "") return "fail 1"
     if (test1(1) != "1") return "fail 2"