Rollup merge of #37694 - michaelwoerister:test-if-ich, r=brson
Rollup merge of #37694 - michaelwoerister:test-if-ich, r=brson

ICH: Add test case for if- and if-let-expressions.

r? @nikomatsakis

GBGamer/rust,aidancully/rust,GBGamer/rust,graydon/rust,aidancully/rust,GBGamer/rust,graydon/rust,aidancully/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust,aidancully/rust,graydon/rust,GBGamer/rust,aidancully/rust,graydon/rust