TypeScript became a build dependency (added in crrev.com/c/7861311, enabled in
crrev.com/c/8104602). Work around it for a system build:

  * Disable the native TypeScript compiler (tsgo) for the WebUI; the JS-based
    compiler bundled with the checkout still works.
  * DevTools already removed that flag (crrev.com/c/8193297), so point its
    typescript.py helper at the system tsc binary (from the 'typescript' package).

Credit: https://github.com/ungoogled-software/ungoogled-chromium/pull/3946

--- a/ui/webui/webui_features.gni
+++ b/ui/webui/webui_features.gni
@@ -33,7 +33,7 @@

   # Enable the native TypeScript compiler (tsgo) instead of the JS-based one.
   # TODO(crbug.com/423789047): Remove this flag once fully committed to v7.
-  use_typescript_go = true
+  use_typescript_go = false
 }

 if (enable_cast_receiver || is_cast_android || is_castos) {
--- a/third_party/devtools-frontend/src/third_party/typescript/typescript.py
+++ b/third_party/devtools-frontend/src/third_party/typescript/typescript.py
@@ -10,6 +10,7 @@


 def GetBinaryPath():
+    return "/usr/bin/tsc"
     if platform.machine() == 'arm64':
         darwin_path = 'mac-arm64'
     else: