[css-navigation-1] Add other: and between: to @navigation.

Author: dbaron

css-navigation-1/Overview.bs

@@ -185,10 +185,15 @@ styles that cause [=view transitions=].
   pattern: url-pattern("/product/:id");
 }
 
-@navigation ((from: --search-results-page) and
-             (to: --product-page)) or
-            ((from: --product-page) and
-             (to: --search-results-page)) {
+@navigation (from: --search-results-page) and
+            (to: --product-page) {
+  /* These styles apply when a navigation is in progress
+     from a search results page to a product page (as
+     defined by the @route rules above), but not in the
+     reverse direction. */
+}
+
+@navigation (between: --search-results-page and --product-page) {
   /* These styles apply when a navigation is in progress
      between a search results page and a product page (as
      defined by the @route rules above), in either
@@ -213,17 +218,24 @@ with <<navigation-condition>> defined as:
                      | <<navigation-in-parens>> [ and <<navigation-in-parens>> ]*
                      | <<navigation-in-parens>> [ or <<navigation-in-parens>> ]*
 <dfn><<navigation-in-parens>></dfn> = ( <<navigation-condition>> ) | ( <<navigation-test>> ) | <<general-enclosed>>
-<dfn><<navigation-test>></dfn> = <<navigation-location-test>> | <<navigation-type-test>>
+<dfn><<navigation-test>></dfn> = <<navigation-location-test>> |
+                    <<navigation-location-between-test>> |
+                    <<navigation-type-test>>
 
 <dfn><<navigation-location-test>></dfn> = <<navigation-location-keyword>> : <<navigation-location>>
-<dfn><<navigation-location-keyword>></dfn> = at | from | to
+<dfn><<navigation-location-keyword>></dfn> = at | other | from | to
 <dfn><<navigation-location>></dfn> = <<route-name>> | <<url-pattern()>>
 <dfn><<route-name>></dfn> = <<dashed-ident>>
 
+<dfn><<navigation-location-between-test>></dfn> =
+    between : <<navigation-location>> and <<navigation-location>>
+
 <dfn><<navigation-type-test>></dfn> = history : <<navigation-type-keyword>>
 <dfn><<navigation-type-keyword>></dfn> = traverse | back | forward | reload
 </pre>
 
+ISSUE: Should we use ''at'' or ''current''?
+
 The above grammar is purposely very loose for forwards-compatibility reasons,
 since the <<general-enclosed>> production
 allows for substantial future extensibility.
@@ -262,6 +274,14 @@ as follows:
         the [=navigation location URL pattern=] of <<navigation-location>>
         and <var>input</var> as the document's [=Document/URL=].
 
+    : other: <<navigation-location>>
+    :: The result is true if
+        the [=current other URL=] <var>other</var> of the document is non-null and
+        [=URL pattern/match|match a URL pattern=] is non-null when
+        given <var>urlPattern</var> as
+        the [=navigation location URL pattern=] of <<navigation-location>>
+        and <var>input</var> as <var>other</var>.
+
     : from: <<navigation-location>>
     :: The result is true if
         the [=current from URL=] <var>from</var> of the document is non-null and
@@ -278,6 +298,20 @@ as follows:
         the [=navigation location URL pattern=] of <<navigation-location>>
         and <var>input</var> as <var>to</var>.
 
+: <<navigation-location-between-test>>
+::    : between: <<navigation-location>> and <<navigation-location>>
+    :: The result is true if
+        the [=current from URL=] <var>from</var> of the document is non-null,
+        the [=current to URL=] <var>to</var> of the document is non-null,
+        [=URL pattern/match|match a URL pattern=] is non-null
+        given <var>urlPattern</var> as
+        the [=navigation location URL pattern=] of one of the two <<navigation-location>>s
+        and <var>input</var> as <var>from</var>, and
+        [=URL pattern/match|match a URL pattern=] is non-null
+        given <var>urlPattern</var> as
+        the [=navigation location URL pattern=] of the other of the two <<navigation-location>>s
+        and <var>input</var> as <var>to</var>.
+
 : <<navigation-type-test>>
 ::    : history: traverse
     :: True if the [=current navigation type=] is {{NavigationType/traverse}}.
@@ -455,6 +489,8 @@ and the pseudo-class matches any element where:
                             navigation-from | navigation-to
 </pre>
 
+ISSUE: Should we use ''navigation-at'' or ''navigation-current''?
+
 A <<link-condition>> matches the target of the link when both:
 * the <<link-condition-base>> matches the target of the link, and
 * either:
@@ -494,7 +530,7 @@ if the following steps return true:
     : If <var>matchTarget</var> is ''navigation-other'',
     :: the <a>current other URL</a> of the document.
     : Otherwise, if <var>matchTarget</var> is ''navigation-current'',
-    :: the <a>current URL</a> of the document.
+    :: the document's [[=Document/URL=]].
     : Otherwise, if <var>matchTarget</var> is ''navigation-from'',
     :: the <a>current from URL</a> of the document.
     : Otherwise (Assert: <var>matchTarget</var> is ''navigation-to''),
@@ -537,7 +573,7 @@ NOTE: Some of the design discussion for this feature has been in
 
 Both the ''@navigation'' rule and the '':link-to()'' pseudo-class
 rely on the following definitions of
-the [=current from URL=] and [=current to URL=].
+the [=current other URL=], [=current from URL=], and [=current to URL=].
 
 The <dfn>current from URL</dfn> of a [=/document=] is a URL or null.
 It is defined as follows:
@@ -628,11 +664,6 @@ ISSUE: The above definitions of from and to apparently don't work right
 if you start a same-document navigation (e.g., with {{History/pushState}})
 in the middle of a cross-document navigation.
 
-The <dfn>current URL</dfn> of a [=/document=] is a URL.
-It is defined as follows:
-
-1. ISSUE: Write this!
-
 The <dfn>current other URL</dfn> of a [=/document=] is a URL or null.
 It is defined as follows: