If the intersection of the types of nodes a and b is empty, then there's
no way that a and b could ever refer to the same object, so we can use
that information for alias analysis.

Drive-by-fix: Improve use of types to enable typed alias analysis to
become more effective. Also fix an ASAN issue uncovered by this CL.

R=jarin@chromium.org

Review-Url: https://codereview.chromium.org/2237433003
Cr-Commit-Position: refs/heads/master@{#38567}