Cherry-pick 272448.257@safari-7618-branch (23c6a88). https://bugs.web…

…kit.org/show_bug.cgi?id=267656

    "ASAN_SEGV | WebCore::Style::resolveForDocument; WebCore::Document::styleForElementIgnoringPendingStylesheets; WebCore::Element::resolveComputedStyle"
    https://bugs.webkit.org/show_bug.cgi?id=267656
    rdar://119187152.

    Reviewed by Ryosuke Niwa.

    Need to prevent attempt to load a disconnected plugin.
    Not adding a new test case as could not make a reliable reproduction of this issue.

    * Source/WebCore/html/HTMLPlugInImageElement.cpp:
    (WebCore::HTMLPlugInImageElement::requestObject):

    Canonical link: https://commits.webkit.org/272448.257@safari-7618-branch

Canonical link: https://commits.webkit.org/266719.400@webkitglib/2.42

Source/WebCore/html/HTMLPlugInImageElement.cpp

@@ -327,6 +327,8 @@ bool HTMLPlugInImageElement::requestObject(const String& relativeURL, const Stri
         return document->frame()->loader().subframeLoader().requestObject(*this, relativeURL, getNameAttribute(), mimeType, paramNames, paramValues);
 
     document->eventLoop().queueTask(TaskSource::Networking, [this, protectedThis = Ref { *this }, document, relativeURL, nameAttribute = getNameAttribute(), mimeType, paramNames, paramValues]() mutable {
+        if (!isConnected())
+            return;
         document->frame()->loader().subframeLoader().requestObject(*this, relativeURL, nameAttribute, mimeType, paramNames, paramValues);
     });
     return true;