JS backend: fix KT-5603 (Multiple catch): add tests

js/js.translator/testData/expression/try/cases/tryCatchThrowable.kt

@@ -0,0 +1,15 @@
+package foo
+
+fun box(): String {
+
+    var s: String = ""
+
+    try {
+        throw Exception()
+    } catch (e: Throwable) {
+        s = "Throwable"
+    }
+    assertEquals("Throwable", s)
+
+    return "OK"
+}