Do not open SELECT popup if the SELECT element is not in the viewport.

third_party/WebKit/Source/core/html/HTMLSelectElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLSelectElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLSelectElement.cpp b/third_party/WebKit/Source/core/html/HTMLSelectElement.cpp
index c1b513711c3747b6df2204199d5be67d57f4eaf1..391b5486f648de1f172eb69a84ebf8c90511dda4 100644
--- a/third_party/WebKit/Source/core/html/HTMLSelectElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLSelectElement.cpp
@@ -1876,9 +1876,12 @@ IntRect HTMLSelectElement::elementRectRelativeToViewport() const
 {
     if (!layoutObject())
         return IntRect();
+    // Initialize with this frame rectangle relative to the viewport.
+    IntRect rect = document().view()->convertToRootFrame(document().view()->boundsRect());
     // We don't use absoluteBoundingBoxRect() because it can return an IntRect
     // larger the actual size by 1px.
-    return document().view()->contentsToViewport(roundedIntRect(layoutObject()->absoluteBoundingBoxFloatRect()));
+    rect.intersect(document().view()->contentsToViewport(roundedIntRect(layoutObject()->absoluteBoundingBoxFloatRect())));
+    return rect;
 }
 
 LayoutUnit HTMLSelectElement::clientPaddingLeft() const
@@ -1951,6 +1954,8 @@ void HTMLSelectElement::showPopup()
         return;
     if (!layoutObject() || !layoutObject()->isMenuList())
         return;
+    if (elementRectRelativeToViewport().isEmpty())
+        return;
 
     if (!m_popup)
         m_popup = document().frameHost()->chromeClient().openPopupMenu(*document().frame(), *this);