Remove unusued lineNumbersGutter fn

It was a copy pasta function from `radicle-explorer` that if we need to
highlight files by line in the future e.g. changesets we should do it
better than this.

src/lib/syntax.ts

@@ -1,4 +1,4 @@
-import type { ElementContent, Root } from "hast";
+import type { Root } from "hast";
 
 import onigurumaWASMUrl from "vscode-oniguruma/release/onig.wasm?url";
 import sourceAsciiDoc from "@wooorm/starry-night/text.html.asciidoc";
@@ -122,118 +122,3 @@ export async function highlight(
   const scope = starryNight.flagToScope(grammar);
   return starryNight.highlight(content, scope ?? "text.raw");
 }
-
-export function lineNumbersGutter(tree: Root) {
-  const replacement: ElementContent[] = [];
-  const search = /\r?\n|\r/g;
-  let index = -1;
-  let start = 0;
-  let startTextRemainder = "";
-  let lineNumber = 0;
-
-  while (++index < tree.children.length) {
-    const child = tree.children[index];
-
-    if (child.type === "text") {
-      let textStart = 0;
-      let match = search.exec(child.value);
-
-      while (match) {
-        // Nodes in this line.
-        const line = tree.children.slice(start, index) as ElementContent[];
-
-        // Prepend text from a partial matched earlier text.
-        if (startTextRemainder) {
-          line.unshift({ type: "text", value: startTextRemainder });
-          startTextRemainder = "";
-        }
-
-        // Append text from this text.
-        if (match.index > textStart) {
-          line.push({
-            type: "text",
-            value: child.value.slice(textStart, match.index),
-          });
-        }
-
-        // Add a line, and the eol.
-        lineNumber += 1;
-        replacement.push(createLine(line, lineNumber), {
-          type: "text",
-          value: match[0],
-        });
-
-        start = index + 1;
-        textStart = match.index + match[0].length;
-        match = search.exec(child.value);
-      }
-
-      // If we matched, make sure to not drop the text after the last line ending.
-      if (start === index + 1) {
-        startTextRemainder = child.value.slice(textStart);
-      }
-    }
-  }
-
-  const line = tree.children.slice(start) as ElementContent[];
-  // Prepend text from a partial matched earlier text.
-  if (startTextRemainder) {
-    line.unshift({ type: "text", value: startTextRemainder });
-    startTextRemainder = "";
-  }
-
-  if (line.length > 0) {
-    lineNumber += 1;
-    replacement.push(createLine(line, lineNumber));
-  }
-
-  // Replace children with new array.
-  tree.children = replacement;
-
-  return tree;
-}
-
-function createLine(children: ElementContent[], line: number): ElementContent {
-  return {
-    type: "element",
-    tagName: "tr",
-    properties: {
-      class: "line",
-      id: "L" + line,
-    },
-    children: [
-      {
-        type: "element",
-        tagName: "td",
-        properties: {
-          className: "line-number",
-        },
-        children: [
-          {
-            type: "element",
-            tagName: "a",
-            properties: { href: "#L" + line },
-            children: [{ type: "text", value: line.toString() }],
-          },
-        ],
-      },
-      {
-        type: "element",
-        tagName: "td",
-        properties: {
-          className: "line-content",
-        },
-        children: [
-          {
-            type: "element",
-            tagName: "pre",
-            properties: {
-              className: "content",
-            },
-            children,
-          },
-        ],
-      },
-    ],
-  };
-}