filter out invisible elements

src/com/dom_distiller/client/DomUtil.java

Index: src/com/dom_distiller/client/DomUtil.java
diff --git a/src/com/dom_distiller/client/DomUtil.java b/src/com/dom_distiller/client/DomUtil.java
index 1450b3b3718c139f9c722349ba12a4e3b2a84db6..214043c62cf148492464ab90667f66acb2eab098 100644
--- a/src/com/dom_distiller/client/DomUtil.java
+++ b/src/com/dom_distiller/client/DomUtil.java
@@ -9,6 +9,7 @@ import com.google.gwt.core.client.JsArray;
 import com.google.gwt.dom.client.Element;
 import com.google.gwt.dom.client.Node;
 import com.google.gwt.dom.client.NodeList;
+import com.google.gwt.dom.client.Style;
 
 public class DomUtil {
     /**
@@ -46,12 +47,33 @@ public class DomUtil {
         NodeList<Element> allElems = root.getElementsByTagName("*");
         for (int i = 0; i < allElems.getLength(); i++) {
             Element elem = allElems.getItem(i);
-            String classAttr = elem.getClassName().toLowerCase();
-            // Make sure |className| is not the substring of another name in |classAttr|, so check
-            // for whitespaces before and after.
-            if ((" " + classAttr + " ").contains(" " + className + " ")) return elem;
+            if (hasClassName(elem, className)) return elem;
         }
         return null;
     }
 
+    public static boolean hasClassName(Element elem, String className) {
+        String classAttr = elem.getClassName().toLowerCase();
+        // Make sure |className| is not the substring of another name in |classAttr|, so check
+        // for whitespaces before and after.
+        return (" " + classAttr + " ").contains(" " + className + " ");
+    }
+
+    /**
+      * @Return The CSS style of an element after applying the active stylesheets and resolving any
+      * basic computation the style's value(s) may contain.
+      * @param el - DOM element
+    */
+    public static native Style getComputedStyle(Element el) /*-{
+      // Standard (includes IE9)

[cjhopman, 2014/05/13 16:20:53]

We don't care about IE.

In everything that we care about (except maybe gwt's test modes),
getComputedStyle is available on the window object, you don't need the
document.defaultView.

So, just:
return getComputedStyle(el, null);

If required for gwt tests, just fall back to el.style (i.e. get rid of the case
for older ie).

[kuan, 2014/05/13 16:55:43]

Done.

+      if (document.defaultView && document.defaultView.getComputedStyle) {
+          return document.defaultView.getComputedStyle(el, null);
+      }
+
+      // Older IE
+      if (el.currentStyle) return el.currentStyle;
+
+      // Inline style
+      return el.style;
+    }-*/;
 }