auto merge of #8027 : nikomatsakis/rust/issue-4846-multiple-lifetime-parameters-1...

Small step towards #4846. r? @msullivan

diff --cc src/librustc/middle/trans/base.rs
Simple merge

diff --cc src/librustc/middle/trans/callee.rs
Simple merge

diff --cc src/librustc/middle/trans/common.rs
Simple merge

diff --cc src/librustc/middle/ty.rs
Simple merge

diff --cc src/librustc/middle/typeck/check/method.rs
Simple merge

diff --cc src/librustc/middle/typeck/check/mod.rs
Simple merge

diff --cc src/librustc/middle/typeck/check/vtable.rs
Simple merge

diff --cc src/librustc/util/ppaux.rs
Simple merge