HTML parser should not associate elements inside templates with forms

Source/core/html/parser/HTMLConstructionSite.cpp

Index: Source/core/html/parser/HTMLConstructionSite.cpp
diff --git a/Source/core/html/parser/HTMLConstructionSite.cpp b/Source/core/html/parser/HTMLConstructionSite.cpp
index 96d3025240f3549ab78e3f2fdb2d2c1581e72e93..c01af71918dbac7ccd5a92f4a3f176a6a585550e 100644
--- a/Source/core/html/parser/HTMLConstructionSite.cpp
+++ b/Source/core/html/parser/HTMLConstructionSite.cpp
@@ -645,10 +645,14 @@ inline Document* HTMLConstructionSite::ownerDocumentForCurrentNode()
 PassRefPtr<Element> HTMLConstructionSite::createHTMLElement(AtomicHTMLToken* token)
 {
     QualifiedName tagName(nullAtom, token->name(), xhtmlNamespaceURI);
+    Document* document = ownerDocumentForCurrentNode();
+    // Only associate the element with the current form if we're creating the new element
+    // in a document with a browsing context (rather than in <template> contents).
+    HTMLFormElement* form = document->frame() ? m_form.get() : 0;
     // FIXME: This can't use HTMLConstructionSite::createElement because we
     // have to pass the current form element.  We should rework form association
     // to occur after construction to allow better code sharing here.
-    RefPtr<Element> element = HTMLElementFactory::createHTMLElement(tagName, ownerDocumentForCurrentNode(), form(), true);
+    RefPtr<Element> element = HTMLElementFactory::createHTMLElement(tagName, document, form, true);
     setAttributes(element.get(), token, m_parserContentPolicy);
     ASSERT(element->isHTMLElement());
     return element.release();