wrong referenced symbol in parameter intializer

[ajafff]

TypeScript Version: 3.1.0-dev.20180831

Search Terms:

Code

// @target: ES2016
let foo = 1;
function test(bar = foo, foo = '') {}

Expected behavior:

foo in the initializer of bar references the parameter foo of type string.
Use before declare error for foo.

Actual behavior:

foo in the initializer of bar references the outer variable declaration foo of type number.
No use before declare error.
Exception when running this code.

Related Issues:
introduced by #26317 while trying to fix #22769
#26762

/cc @Kingwl again