Update variance dep. graph edges to be more fine-grained#31394

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bors merged 3 commits intorust-lang:masterfrom

nikomatsakis:incr-comp-variance

Feb 18, 2016

Commits on Feb 18, 2016

Break the `variance` module into submodules for ease of comprehension.
nikomatsakis
committed
Fix a weird case in the HIR map, where fields are not present in the
nikomatsakis
committed
Change how dep-graph edges are handled in variance to
nikomatsakis
committed