The ConstructFunctionForwardVarargs and ConstructForwardVarargs
builtins, which are used when inlining the Reflect.construct
builtin into TurboFan optimized code, didn't properly check the
new.target parameter whether it's a constructor.

Bug: chromium:752481
Change-Id: I9b8f8c429d6eaed0ff8d27fc3f6b52eb906766a2
Reviewed-on: https://chromium-review.googlesource.com/604187
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47206}