Reland "Implement FullScreen using top layer."

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 063abb03f90b2b3e0d45974732d43eafb74beb80..bf647c99461b486b2c2bfc68179c08868e988820 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -5305,9 +5305,12 @@ void Document::removeFromTopLayer(Element* element)
 
 HTMLDialogElement* Document::activeModalDialog() const
 {
-    if (m_topLayerElements.isEmpty())
-        return 0;
-    return toHTMLDialogElement(m_topLayerElements.last().get());
+    for (auto it = m_topLayerElements.rbegin(); it != m_topLayerElements.rend(); ++it) {

[eae, 2016/07/12 17:09:49]

Why are we iterating backwards here?

[foolip, 2016/07/12 20:19:48]

This is merely because the end of the m_topLayerElements vector is treated as
the top of the top layer stack. In Document::addToTopLayer one can see this, and
I assume it's because pushing/popping at the end of the vector is more
efficient. I'll document this in Document.h.

+        if (isHTMLDialogElement(*it))
+            return toHTMLDialogElement((*it).get());
+    }
+
+    return nullptr;
 }
 
 void Document::exitPointerLock()