Fix font styling in some <h$d> elements

I have discovered the bug when looking at repo commands for the
reviewers plugin, but I have made a pass over all <h$d> elements in
Gerrit's code base and discovered some more problems.

The gr-change-list change will slightly change the UI of the dashboard
page, but users will probably not notice, and generally it will make
the headers more aligned.

Change-Id: Iaae366ea8e2c2121a9bf0a629f81821ce86d6a7d
diff --git a/polygerrit-ui/app/elements/admin/gr-repo-commands/gr-repo-commands_html.ts b/polygerrit-ui/app/elements/admin/gr-repo-commands/gr-repo-commands_html.ts
index 73eb62c..9948f8f 100644
--- a/polygerrit-ui/app/elements/admin/gr-repo-commands/gr-repo-commands_html.ts
+++ b/polygerrit-ui/app/elements/admin/gr-repo-commands/gr-repo-commands_html.ts
@@ -39,11 +39,11 @@
     <div id="loadedContent" class$="[[_computeLoadingClass(_loading)]]">
       <h2 id="options" class="heading-2">Command</h2>
       <div id="form">
-        <h3>Create change</h3>
+        <h3 class="heading-3">Create change</h3>
         <gr-button loading="[[_creatingChange]]" on-click="_createNewChange">
           Create change
         </gr-button>
-        <h3>Edit repo config</h3>
+        <h3 class="heading-3">Edit repo config</h3>
         <gr-button
           id="editRepoConfig"
           loading="[[_editingConfig]]"
@@ -51,7 +51,7 @@
         >
           Edit repo config
         </gr-button>
-        <h3 hidden="[[!_repoConfig.actions.gc.enabled]]">
+        <h3 class="heading-3" hidden="[[!_repoConfig.actions.gc.enabled]]">
           [[_repoConfig.actions.gc.label]]
         </h3>
         <gr-button
diff --git a/polygerrit-ui/app/elements/change-list/gr-change-list/gr-change-list_html.ts b/polygerrit-ui/app/elements/change-list/gr-change-list/gr-change-list_html.ts
index 37d969e..c31da77 100644
--- a/polygerrit-ui/app/elements/change-list/gr-change-list/gr-change-list_html.ts
+++ b/polygerrit-ui/app/elements/change-list/gr-change-list/gr-change-list_html.ts
@@ -63,7 +63,7 @@
               class="cell"
               colspan$="[[_computeColspan(changeSection, visibleChangeTableColumns, labelNames)]]"
             >
-              <h2>
+              <h2 class="heading-3">
                 <a
                   href$="[[_sectionHref(changeSection.query)]]"
                   class="section-title"
diff --git a/polygerrit-ui/app/elements/diff/gr-diff-preferences-dialog/gr-diff-preferences-dialog_html.ts b/polygerrit-ui/app/elements/diff/gr-diff-preferences-dialog/gr-diff-preferences-dialog_html.ts
index 787fe30..85edc12 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-preferences-dialog/gr-diff-preferences-dialog_html.ts
+++ b/polygerrit-ui/app/elements/diff/gr-diff-preferences-dialog/gr-diff-preferences-dialog_html.ts
@@ -49,12 +49,12 @@
   </style>
   <gr-overlay id="diffPrefsOverlay" with-backdrop="">
     <div role="dialog" aria-labelledby="diffPreferencesTitle">
-      <h1
-        class$="diffHeader [[_computeHeaderClass(_diffPrefsChanged)]]"
+      <h3
+        class$="heading-3 diffHeader [[_computeHeaderClass(_diffPrefsChanged)]]"
         id="diffPreferencesTitle"
       >
         Diff Preferences
-      </h1>
+      </h3>
       <gr-diff-preferences
         id="diffPreferences"
         diff-prefs="{{_editableDiffPrefs}}"
diff --git a/polygerrit-ui/app/samples/repo-command.js b/polygerrit-ui/app/samples/repo-command.js
index acecd7d..6abb120 100644
--- a/polygerrit-ui/app/samples/repo-command.js
+++ b/polygerrit-ui/app/samples/repo-command.js
@@ -32,7 +32,7 @@
         margin-bottom: var(--spacing-xxl);
       }
       </style>
-      <h3>Plugin Bork</h3>
+      <h3 class="heading-3">Plugin Bork</h3>
       <gr-button on-click="_handleCommandTap">Bork</gr-button>
     `;
   }