Don't use SVG resource documents with an unrecognized MIME-type

third_party/WebKit/Source/core/svg/SVGUseElement.cpp

Index: third_party/WebKit/Source/core/svg/SVGUseElement.cpp
diff --git a/third_party/WebKit/Source/core/svg/SVGUseElement.cpp b/third_party/WebKit/Source/core/svg/SVGUseElement.cpp
index d07ffa3fede96384bc815b795aa20408853b84bd..155dc2002df7fabaf3931f9651a1a14db718c300 100644
--- a/third_party/WebKit/Source/core/svg/SVGUseElement.cpp
+++ b/third_party/WebKit/Source/core/svg/SVGUseElement.cpp
@@ -146,14 +146,11 @@ TreeScope* SVGUseElement::referencedScope() const
 
 Document* SVGUseElement::externalDocument() const
 {
-    if (m_resource && m_resource->isLoaded()) {
-        // Gracefully handle error condition.
-        if (m_resource->errorOccurred())
-            return nullptr;
-        ASSERT(m_resource->document());
-        return m_resource->document();
-    }
-    return nullptr;
+    // Gracefully handle error condition.
+    if (!resourceIsValid())
+        return nullptr;
+    ASSERT(m_resource->document());
+    return m_resource->document();
 }
 
 void transferUseWidthAndHeightIfNeeded(const SVGUseElement& use, SVGElement* shadowElement, const SVGElement& originalElement)
@@ -789,11 +786,12 @@ void SVGUseElement::dispatchPendingEvent(SVGUseEventSender* eventSender)
 
 void SVGUseElement::notifyFinished(Resource* resource)
 {
+    ASSERT(m_resource == resource);
     if (!inDocument())
         return;
 
     invalidateShadowTree();
-    if (resource->errorOccurred()) {
+    if (!resourceIsValid()) {
         dispatchEvent(Event::create(EventTypeNames::error));
     } else if (!resource->wasCanceled()) {
         if (m_haveFiredLoadEvent)
@@ -811,6 +809,14 @@ bool SVGUseElement::resourceIsStillLoading() const
     return m_resource && m_resource->isLoading();
 }
 
+bool SVGUseElement::resourceIsValid() const
+{
+    return m_resource
+        && m_resource->isLoaded()
+        && !m_resource->errorOccurred()
+        && m_resource->document();
+}
+
 bool SVGUseElement::instanceTreeIsLoading(const SVGElement* targetInstance)
 {
     for (const SVGElement* element = targetInstance; element; element = Traversal<SVGElement>::next(*element, targetInstance)) {