Added PointerEvent.hasPointerCapture API.

third_party/WebKit/Source/core/input/PointerEventManager.cpp

Index: third_party/WebKit/Source/core/input/PointerEventManager.cpp
diff --git a/third_party/WebKit/Source/core/input/PointerEventManager.cpp b/third_party/WebKit/Source/core/input/PointerEventManager.cpp
index 035250a9e5d78a35231a4e32679a4c9dae1eb776..d258c2e85bba0711c5c58fad918864911fb5ecfa 100644
--- a/third_party/WebKit/Source/core/input/PointerEventManager.cpp
+++ b/third_party/WebKit/Source/core/input/PointerEventManager.cpp
@@ -760,6 +760,11 @@ void PointerEventManager::releasePointerCapture(int pointerId, EventTarget* targ
         releasePointerCapture(pointerId);
 }
 
+bool PointerEventManager::hasPointerCapture(int pointerId, EventTarget* target)
+{
+    return m_pendingPointerCaptureTarget.get(pointerId) == target;
+}
+
 void PointerEventManager::releasePointerCapture(int pointerId)
 {
     m_pendingPointerCaptureTarget.remove(pointerId);