Super slow performance when there are lots of "a" html tags

I am displaying an HTML, having about 200 **a** tags, the initial load and display of html is super slow.

When I modify **IsBlockAssignableToBox** function, so it does not add **a** tags, the performance issue is resolved ( and offcourse a tags are not rendered as links)

modifed **IsBlockAssignableToBox** version :

```
private static bool IsBlockAssignableToBox(CssBox box, CssBlock block)
{
bool assignable = true;
if (block.Selectors != null)
{
assignable = IsBlockAssignableToBoxWithSelector(box, block);
}
else if (box.HtmlTag.Name.Equals("a", StringComparison.OrdinalIgnoreCase) && block.Class.Equals("a", StringComparison.OrdinalIgnoreCase)
// && !box.HtmlTag.HasAttribute("href")
)
{
assignable = false;
}

if (assignable && block.Hover)
{
box.HtmlContainer.AddHoverBox(box, block);
assignable = false;
}

return assignable;
}
```

先在載入包含約 200 個 a 標籤的 HTML 文件時，對 IsBlockAssignableToBox 函式進行效能分析，然後將正常路徑與回報的修改進行比較。完成的標準是：文件能夠轉譯連結，且初始載入不會出現嚴重變慢；該 issue 除了此函式之外，沒有指定測試檔案或原始碼檔案。

由索引模型根據 Issue 內容生成。