Formalize fetching and resource timing reporting

Add a generic method to fetch style resources, and make use of it in
fonts & imports.

[css-syntax-3]: Make sure we have a location when parsing a stylesheet.
[css-values-3]: Add a reusable method to fetch a style-originated
resource.
[css-cascade-4]: Formalize the import algorithm to use the new fetch
method.
[css=fonts-4]: Formalize font loading to use the new fetch method.

css-cascade-4/Overview.bs

@@ -265,82 +265,42 @@ Processing Stylesheet Imports</h3>
 	<div algorithm>
 		To <dfn export>fetch an @import</dfn>, given an ''@import'' rule |rule|:
 
+		1. Let |parentStylesheet| be |rule|'s <a spec=cssom for=CSSRule>parent CSS style sheet</a>.
+			[[CSSOM]]
+
 		1. If |rule| has a <<supports-condition>>,
 			and that condition is not true,
-			return nothing.
-
-		1. [=Parse a URL=] given |rule|'s URL,
-			relative to |rule|'s [=CSSRule/parent CSS style sheet's=] [=CSSStyleSheet/location=].
-
-			Issue: Make sure this is defined correctly,
-			drawing from the document when it's a <{style}> element, etc.
-
-			If that fails, then return nothing. Otherwise, let |url| be the [=resulting URL record=].
-
-		2. Let |request| be a new [=/request=]
-			whose [=request/URL=] is |url|,
-			[=request/destination=] is <code>"style"</code>,
-			[=request/mode=] is <code>"no-cors"</code>,
-			[=request/credentials mode=] is <code>"include"</code>,
-			and whose [=request/use-URL-credentials flag=] is set.
-
-		3. Set |request|'s client to ????
-
-			Issue: The Fetch spec doesn't provide any information about what a client is
-			or what it does,
-			so I have no idea of what to provide here.
-
-		4. Run the following steps [=in parallel=]:
+			return.
 
-			1. Let |response| be the result of [=/fetching=] |request|.
+		1. Let |parsedUrl| be the result of the [=URL parser=] steps with |relativeUrl| and
+			|parentStylesheet|'s <a spec=cssom>location</a>. If the algorithm returns an error,
+			return. [[CSSOM]]
 
-			2. Let |success| initially be true.
+		1. [=Fetch a style resource=] |parsedUrl|, with |parentStylesheet|, "style", "no-cors",
+		    and the following steps given [=/response=] |response|:
 
-			3. If |response| is a [=network error=]
-				or its [=response/status=] is not an [=ok status=],
-				set |success| to false.
+			1. If |response| is a [=network error=] or its [=response/status=] is not an
+				[=ok status=], return.
 
-			4. If |rule|'s [=CSSRule/parent style sheet=] is in [=quirks mode=]
+			1. If |parentStylesheet| is in [=quirks mode=]
 				and |response| is [=CORS-same-origin=],
 				let |content type| be <code>"text/css"</code>.
 				Otherwise, let |content type| be the Content Type metadata of |response|.
 
-			5. If |content type| is not <code>"text/css"</code>,
+			1. If |content type| is not <code>"text/css"</code>,
 				return.
 
-			6. Issue: Do we wait for sub-imports to run now?
-				Need to explore this.
+			1. Let |importedStylesheet| be the result of [=Parse a stylesheet|parsing=] |response|'s
+			    [=response/body=]'s [=body/stream=] given |parsedUrl|.
 
-			7. Let |global| be the result of [=finding the relevant global object for a stylesheet=]
-				given |rule|'s [=CSSRule/parent CSS style sheet=].
+			1. Set |importedStylesheet|'s <a spec=cssom>origin-clean flag</a> to
+				|parentStylesheet|'s <a spec=cssom>origin-clean flag</a>.
 
-			8. [=Queue a global task=],
-				given the [=networking task source=]
-				and |global|,
-				to [=process an imported stylesheet=]
-				given |rule|,
-				|success|,
-				and |response|.
-	</div>
-
-	<div algorithm>
-		To <dfn export>find the relevant global object for a stylesheet</dfn> given a CSS style sheet |stylesheet|:
-
-		1. If |stylesheet| has a [=CSSStyleSheet/parent CSS style sheet=],
-			return the result of [=finding the relevant global object for a stylesheet=]
-			given the [=CSSStyleSheet/parent CSS style sheet=].
-
-		2. If |stylesheet| has an [=CSSStyleSheet/owner node=],
-			return the [=CSSStyleSheet/owner node's=] [=relevant global object=].
-	</div>
-
-	<div algorithm>
-		To <dfn export>process an imported stylesheet</dfn>
-		given a parent rule |rule|,
-		a success flag |success|,
-		and a response |response|:
+			1. If |response|'s [=response/url=]'s [=url/origin=] is not the [=same origin=] as
+			    |rule|'s [=relevant settings object=]'s [=environment settings object/origin=],
+				unset |importedStylesheet|'s <a spec=cssom>origin-clean flag</a>.
 
-		Issue: Create a stylesheet, assign it to the parent rule.
+			1. Set |rule|'s {{CSSImportRule/styleSheet}} to |importedStylesheet|.
 	</div>
 
 <h3 id='content-type'>

css-fonts-4/Overview.bs

@@ -2944,9 +2944,18 @@ downloadable fonts to avoid large page reflows where possible.
 <h4 id="font-fetching-requirements" oldids="same-origin-restriction,allowing-cross-origin-font-loading">
 Font fetching requirements</h4>
 
-For font loads from @font-face rules, user agents must create a <a>request</a>
-whose <var>url</var> is the URL given by the @font-face rule, whose <var>referrer</var>
-is the stylesheet's URL, and whose <var>origin</var> is the URL of the containing document.
+<div algorithm>
+	To <dfn>fetch a font</dfn> given a selected [=/url=] |url| for ''@font-face'' |rule|,
+	[=fetch a style resource|fetch=] |url|, with |rule|'s
+	<a spec=cssom for=CSSRule>parent CSS style sheet</a>, "font", "cors" and the following steps
+	given [=/response=] |res|:
+
+	1. Let |body| be |res|'s [=response/body=].
+
+	1. If |body| is null, return.
+
+	1. ISSUE: Load a font from |body| according to its type.
+</div>
 
 Note: The implications of this for authors are that fonts
 will typically not be loaded cross-origin unless authors specifically

css-syntax-3/Overview.bs

@@ -2121,7 +2121,8 @@ Parse A Comma-Separated List According To A CSS Grammar</h4>
 Parse a stylesheet</h4>
 
 	<div algorithm>
-		To <dfn export>parse a stylesheet</dfn> from an |input|:
+		To <dfn export>parse a stylesheet</dfn> from an |input| given [=/url=] or Null |location|
+		(default null):
 
 		<ol>
 			<li>
@@ -2134,7 +2135,7 @@ Parse a stylesheet</h4>
 				and set |input| to the result.
 
 			<li>
-				Create a new stylesheet.
+				Create a new stylesheet, with its <a spec=cssom>location</a> set to |location|.
 
 			<li>
 				<a>Consume a list of rules</a> from |input|,

css-values-4/Overview.bs

@@ -989,6 +989,50 @@ URL Modifiers</h4>
 	Note: A <<url>> that is either unquoted or not wrapped in ''url()'' notation
 	cannot accept any <<url-modifier>>s.
 
+<h4 id='prcoessing-model'>
+URL processing model</h4>
+
+	<div algorithm>
+		To <dfn export>fetch a style resource</dfn> [=/url=] |url|, given a {{CSSStyleSheet}}
+		|sheet|, a string |destination|, a "no-cors" or "cors" |corsMode|, and an algorithm
+		|processResponse| accepting a [=/response=]:
+
+		1. Let |environmentSettings| be |sheet|'s [=relevant settings object=].
+
+		1. Let |global| be |environmentSettings|'s [=environment settings object/global object=].
+
+		1. Let |documentBase| be |environmentSettings|'s [=API base URL=].
+
+		1. Let |base| be |sheet|'s <a spec=cssom>stylesheet base URL</a>. [[CSSOM]]
+
+		1. Let |referrer| be |documentBase|.
+
+		1. Let |handleResourceFetchDone| be to do nothing.
+
+		1. If |base| is null, set |base| to |documentBase|.
+
+		1. Let |parsedUrl| be the result of the [=URL parser=] steps with |url| and |base|.
+			If the algorithm returns an error, return.
+
+		1. If |corsMode| is not "cors", or |url| is the [=same origin=] as |environmentSettings|'s
+			[=environment settings object/origin=], set |referrer| to |sheet|'s
+			<a spec=cssom>location</a>. [[CSSOM]]
+
+		1. Let |req| be a new [=/request=] whose [=request/url=] is |parsedUrl|, whose
+			[=request/destination=] is |destination|, [=request/mode=] is |mode|, [=request/origin=]
+			is |environmentSettings|'s [=environment settings object/origin=],
+			[=request/credentials mode=] is "same-origin", [=request/use-url-credentials flag=] is
+			set, and whose [=request/header list=] is a [=/header list=] containing a [=header=]
+			with its [=header/name=] set to "referrer" and its [=header/value=] set to |referrer|.
+
+		1. If |sheet|'s <a spec=cssom>origin-clean flag</a> is set, set |handleResourceFetchDone|
+			given [=/response=] |res| to [=finalize and report timing=] with |res|, |global|, and
+			<code>"css"</code>. [[CSSOM]]
+
+		1. [=/Fetch=] |req|, with |processResponseDone| set to |handleResourceFetchDone|,
+			|taskDestination| set to |global|, and |processResponse| set to |processResponse|.
+	</div>
+
 <h2 id="numeric-types">
 Numeric Data Types</h2>