Block load event dispatching on old document when an HTMLMediaElement is moved between documents.

Source/core/html/HTMLMediaElement.cpp

Index: Source/core/html/HTMLMediaElement.cpp
diff --git a/Source/core/html/HTMLMediaElement.cpp b/Source/core/html/HTMLMediaElement.cpp
index 82794ff304815ec6a0fe94f87be969867e44ee7b..5d5aad872c97875d0c8ce7eef0e27681c2057f38 100644
--- a/Source/core/html/HTMLMediaElement.cpp
+++ b/Source/core/html/HTMLMediaElement.cpp
@@ -369,9 +369,14 @@ void HTMLMediaElement::didMoveToNewDocument(Document* oldDocument)
     LOG(Media, "HTMLMediaElement::didMoveToNewDocument");
 
     if (m_shouldDelayLoadEvent) {
-        if (oldDocument)
-            oldDocument->decrementLoadEventDelayCount();
         document().incrementLoadEventDelayCount();
+        // Note: Keeping the load event delay count increment on oldDocument that was added
+        // when m_shouldDelayLoadEvent was set so that destruction of m_player can not
+        // cause load event dispatching in oldDocument.
+    } else if (oldDocument) {
+        // Incrementing the load event delay count so that destruction of m_player can not
+        // cause load event dispatching in oldDocument.
+        oldDocument->incrementLoadEventDelayCount();
     }
 
     if (oldDocument)
@@ -386,6 +391,11 @@ void HTMLMediaElement::didMoveToNewDocument(Document* oldDocument)
     // document changes so that playback can be resumed properly.
     userCancelledLoad();
 
+    // Decrement the load event delay count on oldDocument now that m_player has been destroyed
+    // and there is no risk of dispatching a load event from within the destructor.
+    if (oldDocument)
+        oldDocument->decrementLoadEventDelayCount();
+
     HTMLElement::didMoveToNewDocument(oldDocument);
 }