[VE][html5] Ampersands inside href values shouldn't be assumed to be broken character references

To reproduce, markup:

     <a 
href="http://mycoolsite.org/index.jsp?content=something&program=otherthing">

generates the error:

     "& did not start a character reference. (& probably should have been 
escaped as &amp;.)"

This error is probably never helpful in the context of a query string.