Editorial: Minor cleanup / refactor of Manifest processing steps (#1066)

- Fixed call to "process the id member" (removed the document URL argument which
  is not actually accepted by that algorithm).
- Removed unnecessarily complex for loops over ~2 members when it's more
  readable to just have a separate step for each member.
- Use Respec-style syntax instead of HTML.
- Moved default values into individual processing steps. This keeps the relevant
  info about the default values of members closely related to the other relevant
  material about that member. It's also consistent with how the rest of the
  members (e.g. scope) treat default values. And prevents possible errors where
  the incorrect default value is used by an intermediate step in between
  assigning the default and assigning the actual value.

Pre-work for #668.

index.html

@@ -502,6 +502,8 @@ <h3>
           |json:ordered map| and [=ordered map=] |manifest:ordered map|:
         </p>
         <ol class="algorithm">
+          <li>Set |manifest|["dir"] to "auto".
+          </li>
           <li>If |json|["dir"] doesn't [=map/exist=] or if |json|["dir"] is not
           a [=string=], return.
           </li>
@@ -679,6 +681,8 @@ <h3>
           |json:ordered map| and [=ordered map=] |manifest:ordered map|:
         </p>
         <ol class="algorithm">
+          <li>Set |manifest|["display"] to "browser".
+          </li>
           <li>If |json|["display"] doesn't [=map/exist=] or |json|["display"]
           is not a a [=string=], return.
           </li>
@@ -773,6 +777,8 @@ <h3>
           |manifest URL:URL|, and [=URL=] |document URL:URL|:
         </p>
         <ol class="algorithm">
+          <li>Set |manifest|["start_url"] to |document URL|.
+          </li>
           <li>If |json|["start_url"] doesn't [=map/exist=] or
           |json|["start_url"] is not a [=string=], return.
           </li>
@@ -784,8 +790,8 @@ <h3>
           </li>
           <li>If |start URL| is failure, return.
           </li>
-          <li>If |start URL| is not <a>same origin</a> as <var>document
-          URL</var>, return.
+          <li>If |start URL| is not <a>same origin</a> as |document URL|,
+          return.
           </li>
           <li>Otherwise, set |manifest|["start_url"] to |start URL|.
           </li>
@@ -1267,21 +1273,14 @@ <h3>
                 </li>
               </ol>
             </li>
-            <li>Let |manifest:ordered map| be a new [=ordered map=] «[
-            "display" → "browser", "dir" → "auto", "start_url" → |document URL|
-            ]».
+            <li>Let |manifest:ordered map| be an empty [=ordered map=].
             </li>
             <li>[=Process the `dir` member=] passing |json| and |manifest|.
             </li>
             <li>[=Process the `lang` member=] passing |json| and |manifest|.
             </li>
-            <li>[=list/For each=] |member:string| of [=list=] « "name",
-            "short_name" »:
-              <ol>
-                <li>[=Process a text member=] passing |json|, |manifest|, and
-                |member|.
-                </li>
-              </ol>
+            <li>[=Process a text member=] passing |json|, |manifest|, and
+            "name".
             </li>
             <li>[=Process a text member=] passing |json|, |manifest|, and
             "short_name".
@@ -1291,8 +1290,7 @@ <h3>
             <li>[=Process the `start_url` member=] passing |json|, |manifest|,
             |manifest URL|, and |document URL|.
             </li>
-            <li>[=Process the `id` member=] passing |json|, |manifest| and
-            |document URL|.
+            <li>[=Process the `id` member=] passing |json| and |manifest|.
             </li>
             <li>If the [=document=]'s [=document|processed manifest=] is not
             null, and [=document=]'s [=document|processed manifest=]'s id is
@@ -1302,13 +1300,11 @@ <h3>
             <li>[=Process the `scope` member=] passing |json|, |manifest|, and
             |manifest URL|.
             </li>
-            <li>[=list/For each=] |member:string| of [=list=] « "theme_color",
-            "background_color" »:
-              <ol>
-                <li>[=Process a color member=] passing |json|, |manifest|, and
-                |member|.
-                </li>
-              </ol>
+            <li>[=Process a color member=] passing |json|, |manifest|, and
+            "theme_color".
+            </li>
+            <li>[=Process a color member=] passing |json|, |manifest|, and
+            "background_color".
             </li>
             <li>[=Process the `display` member=] passing |json| and |manifest|.
             </li>