KT-2709 Optimizing import removes reference to class when in code val from its class object is used

#KT-2709 Fixed

idea/testData/editor/optimizeImports/Kt2709.kt

@@ -0,0 +1,11 @@
+import MyClass.*
+
+fun main() {
+    TEST
+}
+
+class MyClass {
+    class object {
+        public val TEST: String = ""
+    }
+}

idea/testData/editor/optimizeImports/Kt2709_after.kt

@@ -0,0 +1,11 @@
+import MyClass.*
+
+fun main() {
+    TEST
+}
+
+class MyClass {
+    class object {
+        public val TEST: String = ""
+    }
+}

idea/tests/org/jetbrains/jet/plugin/importOptimizer/OptimizeImportsTest.java

@@ -68,6 +68,10 @@ public class OptimizeImportsTest extends LightCodeInsightTestCase {
         doTest();
     }
 
+    public void testKt2709() throws Exception {
+        doTest();
+    }
+
     public void doTest() throws Exception {
         configureByFile(fileName());
         invokeFormatFile();