Load instance type into a register instead of using memory operands for
several checks on ia32 and x64.

Drive-by: Name used registers in Generate_Call/Generate_Construct

Change-Id: I289c5e420fa03ca639c9b78266560cafb166f6f7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3190099Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Patrick Thier <pthier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77156}