heap: Oilpan library compilation fixes

Bug: 1056170
Change-Id: I467dbaf29f7474550e2fc17b82c6fc7195c4f84e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2627149
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Kentaro Hara <haraken@chromium.org>
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#842963}

third_party/blink/renderer/core/style/data_equivalency.h

@@ -7,14 +7,10 @@
 
 #include <memory>
 #include "base/memory/scoped_refptr.h"
+#include "third_party/blink/renderer/platform/heap/handle.h"
 
 namespace blink {
 
-template <typename T>
-class Persistent;
-template <typename T>
-class Member;
-
 template <typename T>
 bool DataEquivalent(const T* a, const T* b) {
   if (a == b)

third_party/blink/renderer/platform/bindings/active_script_wrappable_base.h

@@ -46,7 +46,7 @@ class PLATFORM_EXPORT ActiveScriptWrappableBase : public GarbageCollectedMixin {
 #if BUILDFLAG(USE_V8_OILPAN)
 
 namespace cppgc {
-template <typename T, typename = void>
+template <typename T, typename Unused>
 struct PostConstructionCallbackTrait;
 
 template <typename T>