KT-2752: fix some tests and make them slightly less fragile

js/js.translator/testData/box/multiModule/_common.kt

@@ -0,0 +1,19 @@
+package helpers
+
+fun checkJsNames(base: String, o: Any) {
+    val regex = Regex("^$base(_[0-9a-zA-Z]+\\\$)?(_[0-9])?$")
+
+    val properties = getAllProperties(o).filter { it.startsWith("$base") }
+    val distinctProperties = properties.mapNotNull { regex.match(it)?.groupValues?.get(1) }.distinct()
+    if (distinctProperties.size != 2) {
+        fail("Two distinct properties expected, ${properties.size} occurred: " + properties)
+    }
+}
+
+fun getAllProperties(o: dynamic): Array<String> = js("""
+    var properties = [];
+    for (property in o) {
+        properties.push(property);
+    }
+    return properties;
+""")