compareDocumentPosition() should report PRECEEDING or FOLLOWING information even if nodes are disco…

Source/core/dom/Node.cpp

Index: Source/core/dom/Node.cpp
diff --git a/Source/core/dom/Node.cpp b/Source/core/dom/Node.cpp
index 40451028714cdc68d6d185eb6649bd53ceb980b1..73c249cdb1e28730d1a69233b26657319751f0fe 100644
--- a/Source/core/dom/Node.cpp
+++ b/Source/core/dom/Node.cpp
@@ -1704,8 +1704,10 @@ unsigned short Node::compareDocumentPositionInternal(const Node* otherNode, Shad
     
     // If either of start1 or start2 is null, then we are disconnected, since one of the nodes is
     // an orphaned attribute node.
-    if (!start1 || !start2)
-        return DOCUMENT_POSITION_DISCONNECTED | DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC;
+    if (!start1 || !start2) {
+        unsigned short direction = (this > otherNode) ? DOCUMENT_POSITION_PRECEDING : DOCUMENT_POSITION_FOLLOWING;
+        return DOCUMENT_POSITION_DISCONNECTED | DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC | direction;
+    }
 
     Vector<const Node*, 16> chain1;
     Vector<const Node*, 16> chain2;
@@ -1739,10 +1741,10 @@ unsigned short Node::compareDocumentPositionInternal(const Node* otherNode, Shad
     // If one node is in the document and the other is not, we must be disconnected.
     // If the nodes have different owning documents, they must be disconnected.  Note that we avoid
     // comparing Attr nodes here, since they return false from inDocument() all the time (which seems like a bug).
-    if (start1->inDocument() != start2->inDocument())
-        return DOCUMENT_POSITION_DISCONNECTED | DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC;
-    if (treatment == TreatShadowTreesAsDisconnected && start1->treeScope() != start2->treeScope())
-        return DOCUMENT_POSITION_DISCONNECTED | DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC;
+    if (start1->inDocument() != start2->inDocument() || (treatment == TreatShadowTreesAsDisconnected && start1->treeScope() != start2->treeScope())) {
+        unsigned short direction = (this > otherNode) ? DOCUMENT_POSITION_PRECEDING : DOCUMENT_POSITION_FOLLOWING;
+        return DOCUMENT_POSITION_DISCONNECTED | DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC | direction;
+    }
 
     // We need to find a common ancestor container, and then compare the indices of the two immediate children.
     const Node* current;
@@ -1756,7 +1758,7 @@ unsigned short Node::compareDocumentPositionInternal(const Node* otherNode, Shad
 
     // If the two elements don't have a common root, they're not in the same tree.
     if (chain1[index1 - 1] != chain2[index2 - 1]) {
-        unsigned short direction = (start1 > start2) ? DOCUMENT_POSITION_PRECEDING : DOCUMENT_POSITION_FOLLOWING;
+        unsigned short direction = (this > otherNode) ? DOCUMENT_POSITION_PRECEDING : DOCUMENT_POSITION_FOLLOWING;
         return DOCUMENT_POSITION_DISCONNECTED | DOCUMENT_POSITION_IMPLEMENTATION_SPECIFIC | direction;
     }