go.tools/go/types: add test case for resolution of blank methods
go.tools/go/types: add test case for resolution of blank methods

(was bug on go/types wishlist; probably fixed a while ago)

R=adonovan
CC=golang-dev
https://codereview.appspot.com/13633047

skyportsystems/go.tools,webfd/go-zh.tools,webfd/go-zh.tools,skyportsystems/go.tools,d0f/go-zh.tools,webfd/go-zh.tools,skyportsystems/go.tools,d0f/go-zh.tools,webfd/go-zh.tools,8limbs/gotools,bryanxu/go-zh.tools,bryanxu/go-zh.tools,8limbs/gotools,skyportsystems/go.tools,bryanxu/go-zh.tools,8limbs/gotools,webfd/go-zh.tools,d0f/go-zh.tools,d0f/go-zh.tools,skyportsystems/go.tools,d0f/go-zh.tools,bryanxu/go-zh.tools,bryanxu/go-zh.tools