This CL fixes the behaviour of the d8.test.fast_c_api constructor when
the global object has been modified by not allowing calls to it without
the `new` keyword.

Bug: chromium:1196597
Change-Id: I49b4a412d501f5c9adaa72b63beec1483ab4c449
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2808943
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73831}