Make isVisible() faster and more accurate

javatests/org/chromium/distiller/DomUtilTest.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.distiller;
 
 import org.chromium.distiller.webdocument.WebTable;
 
 import com.google.gwt.core.client.JsArray;
 import com.google.gwt.dom.client.Document;
@@ skipping 327 matching lines @@
                         "<td>text</td>" +
                         "<td>text</td>" +
                     "</tr>" +
                 "</tbody>" +
             "</table>";
 
         mBody.setInnerHTML(html);
         DomUtil.stripStyleAttributes(mBody);
         assertEquals(expected, mBody.getInnerHTML());
     }
+
+    public void testIsVisibleParentDisplayNone() {
+        String html =
+            "<div style=\"display: none;\">" +
+                "<div>Some Text</div>" +
+            "</div>";
+        mBody.setInnerHTML(html);
+        Element child = mBody.getFirstChildElement().getFirstChildElement();
+        assertFalse(DomUtil.isVisible(child));
+    }
+
+    public void testIsVisibleChildDisplayNone() {
+        String html =
+            "<div>" +
+                "<div style=\"display: none;\">Some Text</div>" +
+            "</div>";
+        mBody.setInnerHTML(html);
+        Element child = mBody.getFirstChildElement().getFirstChildElement();
+        assertFalse(DomUtil.isVisible(child));
+    }
+
+    public void testIsVisibleDisplayBlock() {
+        String html =
+            "<div>" +
+                "<div>Some Text</div>" +
+            "</div>";
+        mBody.setInnerHTML(html);
+        Element child = mBody.getFirstChildElement().getFirstChildElement();
+        assertTrue(DomUtil.isVisible(child));
+    }
 }