Check for the absence of a frame.
This crashes in the situation where the XHR responseXML method is being
called on a document with meta tags.
http://b/issue?id=2346028
diff --git a/WebCore/dom/Document.cpp b/WebCore/dom/Document.cpp
index e4c5741..ef5e69e 100644
--- a/WebCore/dom/Document.cpp
+++ b/WebCore/dom/Document.cpp
@@ -2146,7 +2146,8 @@
         
         String key(buffer.substring(keyBegin, keyEnd - keyBegin));
         String value(buffer.substring(valueBegin, valueEnd - valueBegin));
-        frame()->settings()->setMetadataSettings(key, value);
+        if (frame())
+            frame()->settings()->setMetadataSettings(key, value);
     }
 }
 #endif