cppgc: Don't compress pointers on M1

The CL aims to check if PC is causing a Speedometer regression. The
previous reland was part of the roll that broke builtin PGOs, which
cause large Speedometer2 regression. Now we want to disable and then
reenable pointer compression on M1 just to make sure that there are no
performance regressions caused by PC.

Bug: chromium:1325007
Change-Id: I2442218322d3b045bc5518b03730f57aa2091ebf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3827875Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Auto-Submit: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82435}

BUILD.gn

@@ -837,7 +837,7 @@ if (cppgc_enable_caged_heap) {
   # Always enable young generation compile time flag if caged heap is enabled.
   cppgc_enable_young_generation = true
 
-  if (is_linux || is_mac || is_win) {
+  if (is_linux || (is_mac && v8_current_cpu != "arm64") || is_win) {
     # Always enable on desktop but avoid on ChromeOS for now (for stability
     # reasons).
     cppgc_enable_pointer_compression = true