Move function definition into right #ifdef range

Bug: v8:6666
Change-Id: I23be9d77e7216932bd81cc75e2d5872ce0248c3c
Reviewed-on: https://chromium-review.googlesource.com/958514Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51869}

src/external-reference.cc

@@ -440,11 +440,6 @@ ExternalReference ExternalReference::address_of_real_stack_limit(
   return ExternalReference(isolate->stack_guard()->address_of_real_jslimit());
 }
 
-ExternalReference ExternalReference::address_of_regexp_stack_limit(
-    Isolate* isolate) {
-  return ExternalReference(isolate->regexp_stack()->limit_address());
-}
-
 ExternalReference ExternalReference::store_buffer_top(Isolate* isolate) {
   return ExternalReference(isolate->heap()->store_buffer_top_address());
 }
@@ -619,6 +614,11 @@ ExternalReference ExternalReference::address_of_static_offsets_vector(
       reinterpret_cast<Address>(isolate->jsregexp_static_offsets_vector()));
 }
 
+ExternalReference ExternalReference::address_of_regexp_stack_limit(
+    Isolate* isolate) {
+  return ExternalReference(isolate->regexp_stack()->limit_address());
+}
+
 ExternalReference ExternalReference::address_of_regexp_stack_memory_address(
     Isolate* isolate) {
   return ExternalReference(isolate->regexp_stack()->memory_address());