Make isVisible() faster and more accurate

java/org/chromium/distiller/DomUtil.java

Index: java/org/chromium/distiller/DomUtil.java
diff --git a/java/org/chromium/distiller/DomUtil.java b/java/org/chromium/distiller/DomUtil.java
index d0bcb1bfd7330c1cc8c56be59fdbc6320918284f..4fc01d015d0fcf2e05b771f0695ddbb8b8fada2c 100644
--- a/java/org/chromium/distiller/DomUtil.java
+++ b/java/org/chromium/distiller/DomUtil.java
@@ -95,6 +95,15 @@ public class DomUtil {
     }-*/;
 
     public static boolean isVisible(Element e) {
+        // Detect whether any of the ancestors has "display: none".
+        // Using offsetParent alone wouldn't work because it's also null when position is fixed.
+        return !(e.getOffsetParent() == null && e.getOffsetHeight() == 0 && e.getOffsetWidth() == 0);

[mdjones, 2015/12/08 00:04:33]

why not:
return e.getOffsetParent() != null || ... || ...;

[wychen, 2015/12/08 00:41:46]

Done.

+    }
+
+    // Currently not used by anyone.

[mdjones, 2015/12/08 00:04:33]

I think it's okay if we remove this if not used.

[wychen, 2015/12/08 00:41:46]

Done.

+    public static boolean isVisibleAccurate(Element e) {
+        if (!isVisible(e))
+            return false;
         Style style = getComputedStyle(e);
         double opacity = JavaScript.parseFloat(style.getOpacity());
         return !(style.getDisplay().equals("none") ||