Remove support for the externalResourcesRequired attribute.

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index 00c2016fa9359e21c64a70928aa004df5967e4ef..b519250a2ae6f8a7263ce47753ab41622ae025bb 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -2345,8 +2345,7 @@ void Document::implicitClose()
     }
 
     // To align the HTML load event and the SVGLoad event for the outermost <svg> element, fire it from
-    // here, instead of doing it from SVGElement::finishedParsingChildren (if externalResourcesRequired="false",
-    // which is the default, for ='true' its fired at a later time, once all external resources finished loading).
+    // here, instead of doing it from SVGElement::finishedParsingChildren.
     if (svgExtensions())
         accessSVGExtensions()->dispatchSVGLoadEventToOutermostSVGElements();