Bug 779001. Falling back to Cairo for large canvases. r=roc

gfx/thebes/gfxPlatform.cpp

@@ -690,7 +690,7 @@ gfxPlatform::CreateDrawTargetForBackend(BackendType aBackend, const IntSize& aSi
   if (aBackend == BACKEND_CAIRO) {
     nsRefPtr<gfxASurface> surf = CreateOffscreenSurface(ThebesIntSize(aSize),
                                                         ContentForFormat(aFormat));
-    if (!surf) {
+    if (!surf || surf->CairoStatus()) {
       return NULL;
     }
 

gfx/thebes/gfxWindowsPlatform.cpp

@@ -733,7 +733,7 @@ already_AddRefed<gfxASurface>
 gfxWindowsPlatform::CreateOffscreenSurface(const gfxIntSize& size,
                                            gfxASurface::gfxContentType contentType)
 {
-    gfxASurface *surf = nullptr;
+    nsRefPtr<gfxASurface> surf = nullptr;
 
 #ifdef CAIRO_HAS_WIN32_SURFACE
     if (mRenderMode == RENDER_GDI)
@@ -745,12 +745,11 @@ gfxWindowsPlatform::CreateOffscreenSurface(const gfxIntSize& size,
         surf = new gfxD2DSurface(size, OptimalFormatForContent(contentType));
 #endif
 
-    if (surf == nullptr)
+    if (!surf || surf->CairoStatus()) {
         surf = new gfxImageSurface(size, OptimalFormatForContent(contentType));
+    }
 
-    NS_IF_ADDREF(surf);
-
-    return surf;
+    return surf.forget();
 }
 
 already_AddRefed<gfxASurface>