JS: prevent Any.equals from mangling

js/js.translator/testData/box/native/equalsMangling.js

@@ -0,0 +1,10 @@
+function foo(first, second) {
+    return first.equals(second);
+}
+
+function B(value) {
+    this.value = value;
+}
+B.prototype.equals = function(other) {
+    return other instanceof B && other.value == this.value;
+};

js/js.translator/testData/box/native/equalsMangling.kt

@@ -0,0 +1,25 @@
+data class A(val number: Int)
+
+@native fun foo(first: A, second: A): Boolean
+
+@native class B(value: Int)
+
+fun box(): String {
+    val a = A(23)
+    val b = A(23)
+    val c = A(42)
+
+    if (!foo(a, b)) return "fail1"
+    if (!foo(a, a)) return "fail2"
+    if (foo(a, c)) return "fail3"
+
+    val d = B(23)
+    val e = B(23)
+    val f = B(42)
+
+    if (d != e) return "fail4"
+    if (d != d) return "fail5"
+    if (d == f) return "fail6"
+
+    return "OK"
+}