GCC: fix template specialization in ListHashSetNodeBasePointer

GCC complains that explicit specialization in non-namespace scope
is happening for GetSafe()/SetSafe(). However, secialization is
not really necessary here with templates and can be moved
into GetSafe()/SetSafe() methods without changing generated code.

Bug: 819294
Change-Id: Ib6d7b7760b7b1f3f88a395f5ab3fb4788defbb89
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2010793Reviewed-by: Yuta Kitamura <yutak@chromium.org>
Commit-Queue: Yuta Kitamura <yutak@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735766}

third_party/blink/renderer/platform/wtf/list_hash_set.h

@@ -308,21 +308,16 @@ class ListHashSetNodeBasePointer {
   NodeType& operator*() const { return *Get(); }
 
  private:
-  template <bool = Allocator::kIsGarbageCollected>
   void SetSafe(NodeType* node) {
-    AsAtomicPtr(&node_)->store(node, std::memory_order_relaxed);
-  }
-  template <>
-  void SetSafe<false>(NodeType* node) {
-    node_ = node;
+    if (Allocator::kIsGarbageCollected)
+      AsAtomicPtr(&node_)->store(node, std::memory_order_relaxed);
+    else
+      node_ = node;
   }
 
-  template <bool = Allocator::kIsGarbageCollected>
   NodeType* GetSafe() const {
-    return AsAtomicPtr(&node_)->load(std::memory_order_relaxed);
-  }
-  template <>
-  NodeType* GetSafe<false>() const {
+    if (Allocator::kIsGarbageCollected)
+      return AsAtomicPtr(&node_)->load(std::memory_order_relaxed);
     return node_;
   }