Reland "Keep track of array buffers in new space separately"

src/api.cc

Index: src/api.cc
diff --git a/src/api.cc b/src/api.cc
index c405b875385e4e1ad8235d6148b97f66f2bd7ac2..dc04a950ea36b8543f43dc2449906ce704e3ace1 100644
--- a/src/api.cc
+++ b/src/api.cc
@@ -6531,7 +6531,8 @@ v8::ArrayBuffer::Contents v8::ArrayBuffer::Externalize() {
   Utils::ApiCheck(!self->is_external(), "v8::ArrayBuffer::Externalize",
                   "ArrayBuffer already externalized");
   self->set_is_external(true);
-  isolate->heap()->UnregisterArrayBuffer(self->backing_store());
+  isolate->heap()->UnregisterArrayBuffer(isolate->heap()->InNewSpace(*self),
+                                         self->backing_store());
 
   return GetContents();
 }
@@ -6738,7 +6739,8 @@ v8::SharedArrayBuffer::Contents v8::SharedArrayBuffer::Externalize() {
   Utils::ApiCheck(!self->is_external(), "v8::SharedArrayBuffer::Externalize",
                   "SharedArrayBuffer already externalized");
   self->set_is_external(true);
-  isolate->heap()->UnregisterArrayBuffer(self->backing_store());
+  isolate->heap()->UnregisterArrayBuffer(isolate->heap()->InNewSpace(*self),
+                                         self->backing_store());
   return GetContents();
 }