fix(gerrit): return HTML titles in more cases

At present, we don't return HTML titles if there's a trailing slash,
or a patchset. Instead, just consume the / and anything after it.

This also fixes /123, because this is HTTP redirected to the full path
*with a trailing slash* which otherwise wouldn't get the title
injected.

Change-Id: Idfd0e67752880a37dce0b400a3c1cfc53fac2912
Reviewed-on: https://cl.tvl.fyi/c/depot/+/859
Reviewed-by: BuildkiteCI
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

third_party/gerrit/syntax_highlight_rules_pl.patch

@@ -1,32 +0,0 @@
-diff --git a/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js b/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js
-index 1a0bbd9f50..d8d2fa643b 100644
---- a/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js
-+++ b/polygerrit-ui/app/elements/diff/gr-syntax-layer/gr-syntax-layer.js
-@@ -102,6 +102,10 @@ const LANGUAGE_MAP = {
- };
- const ASYNC_DELAY = 10;
- 
-+const FILENAME_OVERRIDES = {
-+  'rules.pl': 'prolog',
-+};
-+
- const CLASS_WHITELIST = {
-   'gr-diff gr-syntax gr-syntax-attr': true,
-   'gr-diff gr-syntax gr-syntax-attribute': true,
-@@ -233,10 +237,16 @@ class GrSyntaxLayer extends GestureEventListeners(
-     }
-   }
- 
-+  _basename(filename) {
-+    const pieces = filename.split(/\//);
-+    return pieces[pieces.length-1];
-+  }
-+
-   _getLanguage(diffFileMetaInfo) {
-     // The Gerrit API provides only content-type, but for other users of
-     // gr-diff it may be more convenient to specify the language directly.
-     return diffFileMetaInfo.language ||
-+        FILENAME_OVERRIDES[this._basename(diffFileMetaInfo.name)] ||
-         LANGUAGE_MAP[diffFileMetaInfo.content_type];
-   }
-