Revert "[heap] Provide memory order relaxed accessor of page flags."

This reverts commit f29fbf35.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> [heap] Provide memory order relaxed accessor of page flags.
> 
> Bug: chromium:874437,chromium:852420
> Change-Id: I4f484a6bb7072804dbcaacab77d25ba7a3fe338f
> Reviewed-on: https://chromium-review.googlesource.com/1183188
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Hannes Payer <hpayer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#55287}

TBR=ulan@chromium.org,hpayer@chromium.org

Change-Id: I5703641fd99a9dc79e2819af1597d4440e2e9990
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:874437, chromium:852420
Reviewed-on: https://chromium-review.googlesource.com/1185161Reviewed-by: Hannes Payer <hpayer@chromium.org>
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55307}

src/heap/spaces.h

@@ -568,10 +568,7 @@ class MemoryChunk {
 
   void SetFlag(Flag flag) { SetFlags(flag, flag); }
 
-  template <AccessMode access_mode = AccessMode::NON_ATOMIC>
-  bool IsFlagSet(Flag flag) {
-    return (flags<access_mode>() & flag) != 0;
-  }
+  bool IsFlagSet(Flag flag) { return (flags() & flag) != 0; }
 
   void ClearFlag(Flag flag) { flags_ &= ~flag; }
   // Set or clear multiple flags at a time. The flags in the mask are set to
@@ -586,14 +583,7 @@ class MemoryChunk {
   }
 
   // Return all current flags.
-  template <AccessMode access_mode = AccessMode::NON_ATOMIC>
-  uintptr_t flags() {
-    if (access_mode == AccessMode::NON_ATOMIC) {
-      return flags_;
-    } else {
-      return flags_.load(std::memory_order_relaxed);
-    }
-  }
+  uintptr_t flags() { return flags_; }
 
   bool NeverEvacuate() { return IsFlagSet(NEVER_EVACUATE); }