JS: refactor generation of functions with optional parameters. Fix #KT-7302, #KT-13888

js/js.translator/testData/box/defaultArguments/complexExpressionAsConstructorDefaultArgument.kt

@@ -0,0 +1,25 @@
+package foo
+
+var global: String = ""
+
+fun bar(): Int {
+    global += ":bar:"
+    return 100
+}
+
+fun baz() = 1
+
+class A(val x: Int = when (baz()) { 1 -> bar(); else -> 0 })
+
+fun box(): String {
+    global = ""
+    val a1 = A(10)
+    assertEquals(10, a1.x)
+    assertEquals("", global)
+
+    val a2 = A()
+    assertEquals(100, a2.x)
+    assertEquals(":bar:", global)
+
+    return "OK"
+}