JS: move expressions test to box tests

js/js.translator/testData/box/expression/evaluationOrder/elvisComplex.kt

@@ -0,0 +1,22 @@
+package foo
+
+var sideEffect: Int = 0;
+
+class A(val x: Int)
+
+val global_a = A(1)
+val global_b = A(2)
+
+fun nullFun(value: Boolean): Any? = if (value) null else global_a
+
+fun box(): String {
+
+    nullFun(false) ?: global_b
+    assertEquals(global_a, nullFun(false) ?: try { ++sideEffect; global_b } finally {}, "false, global_b")
+    assertEquals(0, sideEffect, "false, global_b side effect")
+
+    assertEquals(global_b, nullFun(true) ?: try { ++sideEffect; global_b } finally {}, "true, global_b")
+    assertEquals(1, sideEffect, "true, global_b side effect")
+
+    return "OK"
+}