Text handling: Display application/json, rather than offering download.

content/handlers/text/textplain.c

@@ -1331,6 +1331,12 @@ nserror textplain_init(void)
 		lwc_string_unref(textplain_default_charset);
 	}
 
+	error = content_factory_register_handler("application/json",
+						 &textplain_content_handler);
+	if (error != NSERROR_OK) {
+		lwc_string_unref(textplain_default_charset);
+	}
+
 	return error;
 }