Implement evaluateJavascript method for Cordova 6

platforms/android/src/org/crosswalk/engine/XWalkWebViewEngine.java

@@ -27,6 +27,7 @@ Licensed to the Apache Software Foundation (ASF) under one
 import android.graphics.Color;
 import android.util.Log;
 import android.view.View;
+import android.webkit.ValueCallback;
 
 import java.io.File;
 import java.io.IOException;
@@ -302,6 +303,16 @@ public void loadUrl(String url, boolean clearNavigationStack) {
         webView.load(url, null);
     }
 
+    /**
+     * This API is used in Cordova-Android 6.0.0 override from
+     *
+     * CordovaWebViewEngine.java
+     * @since Cordova 6.0
+     */
+    public void evaluateJavascript(String js, ValueCallback<String> callback) {
+        webView.evaluateJavascript(js, callback);
+    }
+
     public boolean isXWalkReady() {
         return activityDelegate.isXWalkReady();
     }