heap: Forward termination GC call when using Oilpan library

V8-side change: https://crrev.com/c/2631504

Bug: 1056170
Change-Id: Idd1e1f9d2fcd6804d0d9a010cde83c2fa34a68e2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2636313Reviewed-by: Omer Katz <omerkatz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#844599}

third_party/blink/renderer/platform/heap/v8_wrapper/thread_state.cc

@@ -43,4 +43,8 @@ ThreadState::~ThreadState() {
   DCHECK(IsCreationThread());
 }
 
+void ThreadState::RunTerminationGC() {
+  cpp_heap_.Terminate();
+}
+
 }  // namespace blink

third_party/blink/renderer/platform/heap/v8_wrapper/thread_state.h

@@ -91,6 +91,8 @@ class ThreadState final {
     // TODO(1056170): Remove when removing Oilpan from Blink.
   }
 
+  void RunTerminationGC();
+
  private:
   // Main-thread ThreadState avoids TLS completely by using a regular global.
   // The object is manually managed and should not rely on global ctor/dtor.