ES6 Classes: Remove tracking of super construct calls.

ES6 Classes: Remove tracking of super construct calls.

With the new ES6 semantics super construct calls are only valid in
a constructor in a derived class. This is something that is
statically known and we report early SyntaxError in case it occurs.
We therefore do not need to track this any more.

BUG=v8:3330
LOG=N
R=dslomov@chromium.org, adamk

Review URL: https://codereview.chromium.org/924123002

Cr-Commit-Position: refs/heads/master@{#26644}