[IR] add JsTextTest for IrScript

compiler/testData/ir/irJsText/scripting/safeCalls.kts

@@ -0,0 +1,21 @@
+class Ref(var value: Int)
+
+interface IHost {
+    fun String.extLength() = length
+}
+
+fun test1(x: String?) = x?.length
+fun test2(x: String?) = x?.hashCode()
+fun test3(x: String?, y: Any?) = x?.equals(y)
+
+fun test4(x: Ref?) {
+    x?.value = 0
+}
+
+fun IHost.test5(s: String?) = s?.extLength()
+
+fun Int.foo() = 239
+
+fun box() {
+    42?.foo()
+}