Fixes for re-enabling more MSVC level 4 warnings: Source/core/ edition

Source/core/editing/VisibleUnits.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1270 matching lines @@
         pos = n;
     } while (inSameParagraph(p, pos));
     return pos;
 }
 
 // ---------
 
 VisiblePosition startOfBlock(const VisiblePosition& visiblePosition, EditingBoundaryCrossingRule rule)
 {
     Position position = visiblePosition.deepEquivalent();
-    Node* startBlock;
-    if (!position.containerNode() || !(startBlock = enclosingBlock(position.containerNode(), rule)))
-        return VisiblePosition();
-    return VisiblePosition(firstPositionInNode(startBlock));
+    Node* startBlock = position.containerNode() ? enclosingBlock(position.containerNode(), rule) : 0;
+    return startBlock ? VisiblePosition(firstPositionInNode(startBlock)) : VisiblePosition();
 }
 
 VisiblePosition endOfBlock(const VisiblePosition& visiblePosition, EditingBoundaryCrossingRule rule)
 {
     Position position = visiblePosition.deepEquivalent();
-    Node* endBlock;
-    if (!position.containerNode() || !(endBlock = enclosingBlock(position.containerNode(), rule)))
-        return VisiblePosition();
-    return VisiblePosition(lastPositionInNode(endBlock));
+    Node* endBlock = position.containerNode() ? enclosingBlock(position.containerNode(), rule) : 0;
+    return endBlock ? VisiblePosition(lastPositionInNode(endBlock)) : VisiblePosition();
 }
 
 bool inSameBlock(const VisiblePosition &a, const VisiblePosition &b)
 {
     return !a.isNull() && enclosingBlock(a.deepEquivalent().containerNode()) == enclosingBlock(b.deepEquivalent().containerNode());
 }
 
 bool isStartOfBlock(const VisiblePosition &pos)
 {
     return pos.isNotNull() && pos == startOfBlock(pos, CanCrossEditingBoundary);
@@ skipping 72 matching lines @@
 {
     return direction == LTR ? logicalStartOfLine(c) : logicalEndOfLine(c);
 }
 
 VisiblePosition rightBoundaryOfLine(const VisiblePosition& c, TextDirection direction)
 {
     return direction == LTR ? logicalEndOfLine(c) : logicalStartOfLine(c);
 }
 
 }