Bug 1280753: Call Close() on SVG-in-opentype content viewer, when tearing it down. r=smaug

MozReview-Commit-ID: Jscvj1rvYCp

--HG--
extra : rebase_source : 2f68057e9bda004b8d94ea8685d08170f55906d3

gfx/thebes/gfxSVGGlyphs.cpp

@@ -313,6 +313,7 @@ gfxSVGGlyphsDocument::~gfxSVGGlyphsDocument()
         mPresShell->RemovePostRefreshObserver(this);
     }
     if (mViewer) {
+        mViewer->Close(nullptr);
         mViewer->Destroy();
     }
 }