JS backend: change name mangling -- right now before indexing we sort functions by Visibility and Modality.

(cherry picked from commit 7620a07)

js/js.translator/testFiles/expression/identifierClash/cases/overloadedFun.kt

@@ -0,0 +1,18 @@
+package foo
+
+abstract class B {
+    abstract fun foo(param: String): String
+}
+
+class A : B() {
+    // must be here - before open fun foo(String)
+    private fun foo(param: Int) = "foo(Int)"
+
+    fun foo() = "foo()"
+
+    override fun foo(param: String) = "foo(String)"
+}
+
+fun box(): Boolean {
+    return A().foo("OK") == "foo(String)"
+}