Disabled select element should not fire onchange event.

Source/core/rendering/RenderListBox.cpp

Index: Source/core/rendering/RenderListBox.cpp
diff --git a/Source/core/rendering/RenderListBox.cpp b/Source/core/rendering/RenderListBox.cpp
index 15eed0c8c1e4d2353c3367eff1dc4268c8086ca4..f76cdfae845bd3e19765f5dd8c92afd32129b5ab 100644
--- a/Source/core/rendering/RenderListBox.cpp
+++ b/Source/core/rendering/RenderListBox.cpp
@@ -562,6 +562,9 @@ void RenderListBox::autoscroll(const IntPoint&)
     IntPoint pos = frame()->view()->windowToContents(frame()->eventHandler()->lastKnownMousePosition());
 
     int endIndex = scrollToward(pos);
+    if (selectElement()->isDisabledFormControl())
+        return;
+
     if (endIndex >= 0) {
         HTMLSelectElement* select = selectElement();
         m_inAutoscroll = true;
@@ -577,6 +580,9 @@ void RenderListBox::autoscroll(const IntPoint&)
 
 void RenderListBox::stopAutoscroll()
 {
+    if (selectElement()->isDisabledFormControl())
+        return;
+
     selectElement()->listBoxOnChange();
 }