Scope analysis is over-conservative when treating variable resolutions
as possibly-shadowed by a sloppy eval. In the attached bug, this comes
into play since catch scopes have different behavior with respect to
the "calls eval" in eager vs lazy compilation (in the latter, they
are never marked as "calls eval" because CatchContexts don't have
an associated ScopeInfo).

This patch changes the scope-type check to also eliminate a few other
cases where shadowing isn't possible, such as non-declaration block scopes.

BUG=chromium:608279
LOG=n

Review-Url: https://codereview.chromium.org/1950803002
Cr-Commit-Position: refs/heads/master@{#36046}