message: Few minor updates to VariableSizeAllocationsManager
diff: @@ -164,7 +164,7 @@ public:
  Allocation() {}
  - static constexpr OffsetType InvalidOffset = static_cast<OffsetType>(-1);
  + static constexpr OffsetType InvalidOffset = ~OffsetType{0};
  static Allocation InvalidAllocation()
  {
  return Allocation{InvalidOffset, 0};
  @@ -250,13 +250,14 @@ public:
  void Free(Allocation&& allocation)
  {
  + VERIFY_EXPR(allocation.IsValid());
  Free(allocation.UnalignedOffset, allocation.Size);
  allocation = Allocation{};
  }
  void Free(OffsetType Offset, OffsetType Size)
  {
  - VERIFY_EXPR(Offset + Size <= m_MaxSize);
  + VERIFY_EXPR(Offset != Allocation::InvalidOffset && Offset + Size <= m_MaxSize);
  // Find the first element whose offset is greater than the specified offset.
  // upper_bound() returns an iterator pointing to the first element in the
  