Have Document::accessSVGExtensions() return a reference

Source/core/svg/SVGFitToViewBox.h

Index: Source/core/svg/SVGFitToViewBox.h
diff --git a/Source/core/svg/SVGFitToViewBox.h b/Source/core/svg/SVGFitToViewBox.h
index 6f52a5c53bdead19af5098fb81d45638cf2b50ef..9bdfaac336349ed9fd3bd0e981b3e56a2a7e6c6d 100644
--- a/Source/core/svg/SVGFitToViewBox.h
+++ b/Source/core/svg/SVGFitToViewBox.h
@@ -55,11 +55,11 @@ public:
         if (name == SVGNames::viewBoxAttr) {
             m_viewBox->setBaseValueAsString(value, parseError);
             if (m_viewBox->baseValue()->width() < 0.0f) {
-                document.accessSVGExtensions()->reportError("A negative value for ViewBox width is not allowed");
+                document.accessSVGExtensions().reportError("A negative value for ViewBox width is not allowed");
                 m_viewBox->baseValue()->setInvalid();
             }
             if (m_viewBox->baseValue()->height() < 0.0f) {
-                document.accessSVGExtensions()->reportError("A negative value for ViewBox height is not allowed");
+                document.accessSVGExtensions().reportError("A negative value for ViewBox height is not allowed");
                 m_viewBox->baseValue()->setInvalid();
             }
             return true;