DOMParser: handle use from contexts without an "active document".

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

Index: third_party/WebKit/Source/core/xml/DOMParser.cpp
diff --git a/third_party/WebKit/Source/core/xml/DOMParser.cpp b/third_party/WebKit/Source/core/xml/DOMParser.cpp
index 9bec141914aff5f4600b4304165c26f4243d8bb0..98a2a5bef7479c35e59885685210654957238ccc 100644
--- a/third_party/WebKit/Source/core/xml/DOMParser.cpp
+++ b/third_party/WebKit/Source/core/xml/DOMParser.cpp
@@ -28,7 +28,8 @@ Document* DOMParser::parseFromString(const String& str, const String& type) {
   Document* doc = DOMImplementation::createDocument(
       type, DocumentInit(KURL(), nullptr, m_contextDocument), false);
   doc->setContent(str);
-  doc->setSecurityOrigin(m_contextDocument->getSecurityOrigin());
+  if (m_contextDocument)
+    doc->setSecurityOrigin(m_contextDocument->getSecurityOrigin());
   return doc;
 }