This is currently done by generating a default constructor that looks
like this:

  constructor() {
    %DefaultConstructorSuperCall();
  }

The a runtime function implements the logic which is pretty similar to
Runtime_Apply except that it uses the [[Prototype]] of the current
function.

BUG=v8:3672
LOG=Y
R=dslomov@chromium.org

Review URL: https://codereview.chromium.org/692333011

Cr-Commit-Position: refs/heads/master@{#25268}
git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@25268 ce2b1a6d-e550-0410-aec6-3dcde31c8c00