JS backend: add RegressionMergeEcmaTest

js/js.translator/testFiles/mergeEcma/cases/objectWithMethods.kt

@@ -0,0 +1,22 @@
+package foo
+
+class Test {
+  private val a = object {
+      fun c() = 3
+      fun b() = 2
+  }
+
+  fun doTest(): Boolean {
+    if (a.c() != 3) {
+        return false;
+    }
+    if (a.b() != 2) {
+        return false;
+    }
+    return true;
+  }
+}
+
+fun box(): Boolean {
+    return Test().doTest();
+}