Revert of Provide a tagged allocation top pointer.

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 51afa7b19aa88788a9f138a3e2c25161389fbf1d..97f9de996f6cc8abd753072b4c003ac36bb4add9 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -1635,39 +1635,51 @@
 // space.
 class AllocationInfo {
  public:
-  AllocationInfo() { Reset(nullptr, nullptr); }
-  AllocationInfo(Address top, Address limit) { Reset(top, limit); }
+  AllocationInfo() : top_(nullptr), limit_(nullptr) {}
+  AllocationInfo(Address top, Address limit) : top_(top), limit_(limit) {}
 
   void Reset(Address top, Address limit) {
     set_top(top);
     set_limit(limit);
   }
 
-  inline void set_top(Address top) {
-    SLOW_DCHECK((reinterpret_cast<intptr_t>(top) & kHeapObjectTagMask) == 0);
-    top_ = reinterpret_cast<intptr_t>(top) + kHeapObjectTag;
-  }
-
-  inline Address top() const {
-    SLOW_DCHECK((top_ & kHeapObjectTagMask) == kHeapObjectTag);
-    return reinterpret_cast<Address>(top_ - kHeapObjectTag);
-  }
-
-  Address* top_address() { return reinterpret_cast<Address*>(&top_); }
-
-  inline void set_limit(Address limit) {
-    limit_ = reinterpret_cast<intptr_t>(limit);
-  }
-
-  inline Address limit() const { return reinterpret_cast<Address>(limit_); }
-
-  Address* limit_address() { return reinterpret_cast<Address*>(&limit_); }
+  INLINE(void set_top(Address top)) {
+    SLOW_DCHECK(top == NULL ||
+                (reinterpret_cast<intptr_t>(top) & kHeapObjectTagMask) == 0);
+    top_ = top;
+  }
+
+  INLINE(Address top()) const {
+    SLOW_DCHECK(top_ == NULL ||
+                (reinterpret_cast<intptr_t>(top_) & kHeapObjectTagMask) == 0);
+    return top_;
+  }
+
+  Address* top_address() { return &top_; }
+
+  INLINE(void set_limit(Address limit)) {
+    limit_ = limit;
+  }
+
+  INLINE(Address limit()) const {
+    return limit_;
+  }
+
+  Address* limit_address() { return &limit_; }
+
+#ifdef DEBUG
+  bool VerifyPagedAllocation() {
+    return (Page::FromAllocationAreaAddress(top_) ==
+            Page::FromAllocationAreaAddress(limit_)) &&
+           (top_ <= limit_);
+  }
+#endif
 
  private:
-  // Current tagged allocation top.
-  intptr_t top_;
-  // Current untagged allocation limit.
-  intptr_t limit_;
+  // Current allocation top.
+  Address top_;
+  // Current allocation limit.
+  Address limit_;
 };