Simplify Attr code in XPathUtil

Now that Attr never has childen, a Text node can't have an Attr parent,
and so the condition would always return true.

BUG=305105
R=tkent@chromium.org

Review-Url: https://codereview.chromium.org/2342163004
Cr-Commit-Position: refs/heads/master@{#419490}

third_party/WebKit/Source/core/xml/XPathUtil.cpp

@@ -72,6 +72,7 @@ bool isValidContextNode(Node* node)
         return false;
     switch (node->getNodeType()) {
     case Node::kAttributeNode:
+    case Node::kTextNode:
     case Node::kCdataSectionNode:
     case Node::kCommentNode:
     case Node::kDocumentNode:
@@ -81,8 +82,6 @@ bool isValidContextNode(Node* node)
     case Node::kDocumentFragmentNode:
     case Node::kDocumentTypeNode:
         return false;
-    case Node::kTextNode:
-        return !(node->parentNode() && node->parentNode()->isAttributeNode());
     }
     NOTREACHED();
     return false;