Remove useless null checks from Node::document() call sites

Source/core/page/EventHandler.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org)
  * Copyright (C) 2012 Digia Plc. and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
@@ skipping 3624 matching lines @@
             // Touch events should not go to text nodes
             if (node->isTextNode())
                 node = EventPathWalker::parent(node);
 
             Document* doc = node->document();
             // Record the originating touch document even if it does not have a touch listener.
             if (freshTouchEvents) {
                 m_originatingTouchPointDocument = doc;
                 freshTouchEvents = false;
             }
-            if (!doc)
-                continue;
             if (!doc->hasTouchEventHandlers())
                 continue;
             m_originatingTouchPointTargets.set(touchPointTargetKey, node);
             touchTarget = node;
         } else if (pointState == PlatformTouchPoint::TouchReleased || pointState == PlatformTouchPoint::TouchCancelled) {
             // We only perform a hittest on release or cancel to unset :active or :hover state.
             if (touchPointTargetKey == m_originatingTouchPointTargetKey) {
                 hitTestResultAtPoint(pagePoint, hitType);
                 m_originatingTouchPointTargetKey = 0;
             } else if (m_originatingTouchPointDocument.get() && m_originatingTouchPointDocument->frame()) {
                 LayoutPoint pagePointInOriginatingDocument = documentPointForWindowPoint(m_originatingTouchPointDocument->frame(), point.pos());
                 hitTestResultInFrame(m_originatingTouchPointDocument->frame(), pagePointInOriginatingDocument, hitType);
             }
             // The target should be the original target for this touch, so get it from the hashmap. As it's a release or cancel
             // we also remove it from the map.
             touchTarget = m_originatingTouchPointTargets.take(touchPointTargetKey);
         } else
             // No hittest is performed on move or stationary, since the target is not allowed to change anyway.
             touchTarget = m_originatingTouchPointTargets.get(touchPointTargetKey);
 
         if (!touchTarget.get())
             continue;
         Document* doc = touchTarget->toNode()->document();
-        if (!doc)
-            continue;
         if (!doc->hasTouchEventHandlers())
             continue;
         Frame* targetFrame = doc->frame();
         if (!targetFrame)
             continue;
 
         if (m_frame != targetFrame) {
             // pagePoint should always be relative to the target elements containing frame.
             pagePoint = documentPointForWindowPoint(targetFrame, point.pos());
         }
@@ skipping 170 matching lines @@
 unsigned EventHandler::accessKeyModifiers()
 {
 #if OS(DARWIN)
     return PlatformEvent::CtrlKey | PlatformEvent::AltKey;
 #else
     return PlatformEvent::AltKey;
 #endif
 }
 
 } // namespace WebCore