Implement MouseEvent buttons attribute.

Source/core/events/MouseEvent.cpp

Index: Source/core/events/MouseEvent.cpp
diff --git a/Source/core/events/MouseEvent.cpp b/Source/core/events/MouseEvent.cpp
index b875392efae6270299157517467d31203ea4265d..bdfdd1f799e9516d305c63a3674dab75d45c1ad7 100644
--- a/Source/core/events/MouseEvent.cpp
+++ b/Source/core/events/MouseEvent.cpp
@@ -40,6 +40,7 @@ MouseEventInit::MouseEventInit()
     , shiftKey(false)
     , metaKey(false)
     , button(0)
+    , buttons(0)
     , relatedTarget(nullptr)
 {
 }
@@ -61,24 +62,27 @@ PassRefPtrWillBeRawPtr<MouseEvent> MouseEvent::create(const AtomicString& eventT
         eventType, isBubbling, isCancelable, view,
         detail, event.globalPosition().x(), event.globalPosition().y(), event.position().x(), event.position().y(),
         event.movementDelta().x(), event.movementDelta().y(),
-        event.ctrlKey(), event.altKey(), event.shiftKey(), event.metaKey(), event.button(),
+        event.ctrlKey(), event.altKey(), event.shiftKey(), event.metaKey(), event.button(), event.buttons(),
         relatedTarget, nullptr, false, event.syntheticEventType());
 }
 
 PassRefPtrWillBeRawPtr<MouseEvent> MouseEvent::create(const AtomicString& type, bool canBubble, bool cancelable, PassRefPtrWillBeRawPtr<AbstractView> view,
     int detail, int screenX, int screenY, int pageX, int pageY,
     int movementX, int movementY,
-    bool ctrlKey, bool altKey, bool shiftKey, bool metaKey, unsigned short button,
+    bool ctrlKey, bool altKey, bool shiftKey, bool metaKey,
+    unsigned short button, unsigned short buttons,
     PassRefPtrWillBeRawPtr<EventTarget> relatedTarget, PassRefPtrWillBeRawPtr<DataTransfer> dataTransfer, bool isSimulated, PlatformMouseEvent::SyntheticEventType syntheticEventType)
 {
     return adoptRefWillBeNoop(new MouseEvent(type, canBubble, cancelable, view,
         detail, screenX, screenY, pageX, pageY,
         movementX, movementY,
-        ctrlKey, altKey, shiftKey, metaKey, button, relatedTarget, dataTransfer, isSimulated, syntheticEventType));
+        ctrlKey, altKey, shiftKey, metaKey, button, buttons,
+        relatedTarget, dataTransfer, isSimulated, syntheticEventType));
 }
 
 MouseEvent::MouseEvent()
     : m_button(0)
+    , m_buttons(0)
     , m_buttonDown(false)
 {
 }
@@ -87,13 +91,14 @@ MouseEvent::MouseEvent(const AtomicString& eventType, bool canBubble, bool cance
     int detail, int screenX, int screenY, int pageX, int pageY,
     int movementX, int movementY,
     bool ctrlKey, bool altKey, bool shiftKey, bool metaKey,
-    unsigned short button, PassRefPtrWillBeRawPtr<EventTarget> relatedTarget,
+    unsigned short button, unsigned short buttons, PassRefPtrWillBeRawPtr<EventTarget> relatedTarget,
     PassRefPtrWillBeRawPtr<DataTransfer> dataTransfer, bool isSimulated, PlatformMouseEvent::SyntheticEventType syntheticEventType)
     : MouseRelatedEvent(eventType, canBubble, cancelable, view, detail, IntPoint(screenX, screenY),
                         IntPoint(pageX, pageY),
                         IntPoint(movementX, movementY),
                         ctrlKey, altKey, shiftKey, metaKey, isSimulated)
     , m_button(button == (unsigned short)-1 ? 0 : button)
+    , m_buttons(buttons)
     , m_buttonDown(button != (unsigned short)-1)
     , m_relatedTarget(relatedTarget)
     , m_dataTransfer(dataTransfer)
@@ -107,6 +112,7 @@ MouseEvent::MouseEvent(const AtomicString& eventType, const MouseEventInit& init
         IntPoint(0 /* movementX */, 0 /* movementY */),
         initializer.ctrlKey, initializer.altKey, initializer.shiftKey, initializer.metaKey, false /* isSimulated */)
     , m_button(initializer.button == (unsigned short)-1 ? 0 : initializer.button)
+    , m_buttons(initializer.buttons)
     , m_buttonDown(initializer.button != (unsigned short)-1)
     , m_relatedTarget(initializer.relatedTarget)
     , m_dataTransfer(nullptr)
@@ -205,7 +211,7 @@ SimulatedMouseEvent::~SimulatedMouseEvent()
 }
 
 SimulatedMouseEvent::SimulatedMouseEvent(const AtomicString& eventType, PassRefPtrWillBeRawPtr<AbstractView> view, PassRefPtrWillBeRawPtr<Event> underlyingEvent)
-    : MouseEvent(eventType, true, true, view, 0, 0, 0, 0, 0, 0, 0, false, false, false, false, 0,
+    : MouseEvent(eventType, true, true, view, 0, 0, 0, 0, 0, 0, 0, false, false, false, false, 0, 0,
         nullptr, nullptr, true, PlatformMouseEvent::RealOrIndistinguishable)
 {
     if (UIEventWithKeyState* keyStateEvent = findEventWithKeyState(underlyingEvent.get())) {
@@ -272,9 +278,9 @@ bool MouseEventDispatchMediator::dispatchEvent(EventDispatcher* dispatcher) cons
     // as a separate event in other DOM-compliant browsers like Firefox, and so we do the same.
     RefPtrWillBeRawPtr<MouseEvent> doubleClickEvent = MouseEvent::create();
     doubleClickEvent->initMouseEvent(EventTypeNames::dblclick, event()->bubbles(), event()->cancelable(), event()->view(),
-                                     event()->detail(), event()->screenX(), event()->screenY(), event()->clientX(), event()->clientY(),
-                                     event()->ctrlKey(), event()->altKey(), event()->shiftKey(), event()->metaKey(),
-                                     event()->button(), relatedTarget);
+        event()->detail(), event()->screenX(), event()->screenY(), event()->clientX(), event()->clientY(),
+        event()->ctrlKey(), event()->altKey(), event()->shiftKey(), event()->metaKey(),
+        event()->button(), relatedTarget);
     if (event()->defaultHandled())
         doubleClickEvent->setDefaultHandled();
     EventDispatcher::dispatchEvent(dispatcher->node(), MouseEventDispatchMediator::create(doubleClickEvent));