[css-syntax] Allow the parser algorithms to be invoked on a string.

Author: tabatkins

css-syntax/Overview.html

@@ -2941,13 +2941,12 @@ <h3 id=definitions0><span class=secno>5.2. </span> Definitions</h3>
       <h3 id=parser-entry-points><span class=secno>5.3. </span> Parser Entry
        Points</h3>
 
-      <p> The algorithms defined in this specification can be invoked in
-       multiple ways to convert a stream of text into various CSS concepts.
-
-      <p> All of the algorithms defined in this section begin in the parser.
-       It is assumed that the <a href="#preprocessing-the-input-stream">input
-       preprocessing</a> and <a href="#tokenization">tokenization</a> steps
-       have already been completed, resulting in a stream of tokens.
+      <p> The algorithms defined in this section produce high-level CSS
+       objects from lower-level objects. They assume that they are invoked on
+       a token stream, but they may also be invoked on a string; if so, first
+       perform <a href="#preprocessing-the-input-stream">input
+       preprocessing</a> to produce a character stream, then perform <a
+       href="#tokenization">tokenization</a> to produce a token stream.
 
       <p class=note> Other specs can define additional entry points for their
        own purposes.

css-syntax/Overview.src.html

@@ -1902,15 +1902,15 @@ <h3>
 Parser Entry Points</h3>
 
 	<p>
-		The algorithms defined in this specification can be invoked in multiple ways
-		to convert a stream of text into various CSS concepts.
-
-	<p>
-		All of the algorithms defined in this section begin in the parser.
-		It is assumed that the <a href="#preprocessing-the-input-stream">input preprocessing</a>
-		and <a href="#tokenization">tokenization</a>
-		steps have already been completed,
-		resulting in a stream of tokens.
+		The algorithms defined in this section produce high-level CSS objects
+		from lower-level objects.
+		They assume that they are invoked on a token stream,
+		but they may also be invoked on a string;
+		if so,
+		first perform <a href="#preprocessing-the-input-stream">input preprocessing</a>
+		to produce a character stream,
+		then perform <a href="#tokenization">tokenization</a>
+		to produce a token stream.
 
 	<p class='note'>
 		Other specs can define additional entry points for their own purposes.