[core] Remove debug-only setTimeout().
[core] Remove debug-only setTimeout().

When using --custom-devtools-frontend (or other means that trigger
'debugFrontend' parameter to be set to true), dispatching of browser
messages is delayed via an additional `setTimeout`. This however causes
trouble for example with context menu selection events, where it races
with the removal of the menu item event listeners.

Fixed: chromium:1266826
Change-Id: Idcb0ba5b19854cefcf5a3f8ca2bb2a617ec047e9
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/3259698
Reviewed-by: Tim van der Lippe <dba8716ee7f8d16236046f74d2167cb94410f6ed@chromium.org>
Commit-Queue: Benedikt Meurer <024a1e0af501338d11c3b837c6193d11c140d792@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend