[JS] Add test for KT-39378

js/js.translator/testData/box/jsModule/kt39378.js

@@ -0,0 +1,5 @@
+function ee() {
+    return {
+        ss: ['O' , 'K']
+    }
+}

js/js.translator/testData/box/jsModule/kt39378.kt

@@ -0,0 +1,34 @@
+// EXPECTED_REACHABLE_NODES: 1238
+
+// MODULE: lib
+// FILE: l.kt
+
+package l
+
+external interface E {
+    var ss: Array<String> // Effectively external property.
+}
+
+external fun ee(): E
+
+fun foo(): String {
+
+    val e = ee()
+
+    var result =  ""
+
+    for (s in e.ss) {
+        result += s
+    }
+
+    return result
+}
+
+// MODULE: main(lib)
+// FILE: m.kt
+
+import l.*
+
+fun box(): String {
+    return foo()
+}