cppgc: Prohibit Oilpan usage from within V8

Until setup and general API direction are clear no C++ types should be
GCed.

Bug: chromium:1056170
Change-Id: I9d51e57065b22f025898114d20887166ef756319
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3116256Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#76480}

src/DEPS

@@ -66,6 +66,10 @@ include_rules = [
   "+builtins-generated",
   "+torque-generated",
   "+starboard",
+  # Using cppgc inside v8 is not (yet) allowed.
+  "-include/cppgc",
+  "+include/cppgc/platform.h",
+  "+include/cppgc/source-location.h",
 ]
 
 specific_include_rules = {

src/api/api.cc

@@ -11,7 +11,6 @@
 #include <utility>  // For move
 #include <vector>
 
-#include "include/cppgc/custom-space.h"
 #include "include/v8-callbacks.h"
 #include "include/v8-cppgc.h"
 #include "include/v8-date.h"

src/heap/cppgc-js/DEPS

+include_rules = [
+  "+include/cppgc",
+]

src/heap/cppgc/DEPS

+include_rules = [
+  "+include/cppgc",
+]