go.tools/dashboard: fix integration test
go.tools/dashboard: fix integration test

LGTM=dvyukov
R=dvyukov
CC=golang-codereviews
https://codereview.appspot.com/126700043

webfd/go-zh.tools,webfd/go-zh.tools,webfd/go-zh.tools,skyportsystems/go.tools,d0f/go-zh.tools,bryanxu/go-zh.tools,skyportsystems/go.tools,bryanxu/go-zh.tools,bryanxu/go-zh.tools,d0f/go-zh.tools,bryanxu/go-zh.tools,skyportsystems/go.tools,d0f/go-zh.tools,skyportsystems/go.tools,webfd/go-zh.tools,skyportsystems/go.tools,webfd/go-zh.tools,bryanxu/go-zh.tools,d0f/go-zh.tools,d0f/go-zh.tools