Bug 915940. Only report memory allocated from gfxWindowsSurfaces if it is actually allocated. r=jrmuizel

gfx/thebes/gfxWindowsSurface.cpp

@@ -60,12 +60,12 @@ gfxWindowsSurface::gfxWindowsSurface(const gfxIntSize& realSize, gfxImageFormat
 
     Init(surf);
 
-    RecordMemoryUsed(size.width * size.height * 4 + sizeof(gfxWindowsSurface));
-
-    if (CairoStatus() == 0)
+    if (CairoStatus() == CAIRO_STATUS_SUCCESS) {
         mDC = cairo_win32_surface_get_dc(CairoSurface());
-    else
+        RecordMemoryUsed(size.width * size.height * 4 + sizeof(gfxWindowsSurface));
+    } else {
         mDC = nullptr;
+    }
 }
 
 gfxWindowsSurface::gfxWindowsSurface(HDC dc, const gfxIntSize& realSize, gfxImageFormat imageFormat) :