This makes new.target work in [[Call]] and [[Construct]] of ordinary
functions.

We achieve this by introducing a new construct stub for functions that
uses the new.target variable. The construct stub pushes the original
constructor just above the receiver in the construct frame.

BUG=v8:3887
LOG=N
R=adamk@chromium.org, dslomov@chromium.org

Review URL: https://codereview.chromium.org/1203813002

Cr-Commit-Position: refs/heads/master@{#29358}