Don't turn middleclicks into click events.

Source/core/page/EventHandler.cpp

Index: Source/core/page/EventHandler.cpp
diff --git a/Source/core/page/EventHandler.cpp b/Source/core/page/EventHandler.cpp
index 4ba7e9154a65e0b942cb9f24ebf8e49e79547750..809c5a20f1600bfb0db9ffdfff878c0a7810c13f 100644
--- a/Source/core/page/EventHandler.cpp
+++ b/Source/core/page/EventHandler.cpp
@@ -1655,8 +1655,21 @@ bool EventHandler::handleMouseReleaseEvent(const PlatformMouseEvent& mouseEvent)
     if (mouseEvent.button() == LeftButton && mouseEvent.modifiers() & PlatformEvent::CtrlKey)
         contextMenuEvent = true;
 #endif
-
-    bool swallowClickEvent = m_clickCount > 0 && !contextMenuEvent && mouseIsReleasedOnPressedElement(mev.targetNode(), m_clickNode.get()) && !dispatchMouseEvent(eventNames().clickEvent, mev.targetNode(), true, m_clickCount, mouseEvent, true);
+    bool isMiddleOnLink = false;
+    if (mouseEvent.button() == MiddleButton) {
+        // Middle clicks on links result in the links being opened in a background tab. It's important to not also
+        // dispatch a click event since that might make the link execute twice.
+        WebCore::Node* node = mev.targetNode();

[abarth-chromium, 2013/09/06 05:01:25]

"WebCore::" <-- no need for this namespace.  We're already in the WebCore
namespace.

+        while (node && !node->isLink())
+            node = node->parentNode();

[abarth-chromium, 2013/09/06 05:01:25]

Hum...  This crawling around the DOM doesn't seem like it can be right.

+        if (node)
+            isMiddleOnLink = true;
+    }
+    bool swallowClickEvent = false;
+    if (m_clickCount > 0 && !contextMenuEvent && !isMiddleOnLink && mouseIsReleasedOnPressedElement(mev.targetNode(), m_clickNode.get())) {
+        // Turn the Mouse Button Released event into a click event since all requirements are fulfilled.
+        swallowClickEvent = !dispatchMouseEvent(eventNames().clickEvent, mev.targetNode(), true, m_clickCount, mouseEvent, true);
+    }
 
     if (m_resizeLayer) {
         m_resizeLayer->setInResizeMode(false);