Fix a bug of drop document;

need keep page obj when load page.

Author: greatriver

source/pdf/pdf-interpret.c

@@ -107,6 +107,8 @@ pdf_process_keyword(hd_context *ctx, pdf_processor *proc, pdf_csi *csi, hd_strea
                 font = load_font_or_hail_mary(ctx, csi->doc, fontobj);
                 hd_try(ctx)
                     proc->op_Tf(ctx, proc, csi->name, font, s[0]);
+                hd_always(ctx)
+                    pdf_drop_font(ctx, font);
                 hd_catch(ctx)
                     hd_rethrow(ctx);
             }

source/pdf/pdf-page.c

@@ -221,7 +221,7 @@ pdf_load_page(hd_context *ctx, pdf_document *doc, int number)
         hd_rethrow(ctx);
 
     page = pdf_new_page(ctx, doc);
-    page->obj = pageobj;//pdf_keep_obj(ctx, pageobj);
+    page->obj = pdf_keep_obj(ctx, pageobj);
     return page;
 
 }