[css3-syntax] Make sure a bad token is flagged as a parse error.

Author: tabatkins

css3-syntax/Overview.html

@@ -3434,7 +3434,8 @@ <h3 id=consume-a-primitive><span class=secno>5.4. </span> <dfn
 
   <p> Otherwise, if the <a href="#current-input-token"><i>current input
    token</i></a> is a cdo token, cdc token, } token, ] token, ) token,
-   bad-string token, or bad-url token, return nothing.
+   bad-string token, or bad-url token, this is a <i>parse error</i>. Return
+   nothing.
 
   <p> Otherwise, return the <a href="#current-input-token"><i>current input
    token</i></a>.

css3-syntax/Overview.src.html

@@ -2936,7 +2936,8 @@ <h3>
 		) token,
 		bad-string token,
 		or bad-url token,
-		return nothing.
+		this is a <i>parse error</i>.
+		Return nothing.
 
 	<p>
 		Otherwise, return the <i>current input token</i>.