[WebNFC] Remove unreached code in unit test.

Bug: 346399
Change-Id: I038233ae521749c4168f08bb9450309da4a04e4a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2102492Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Auto-Submit: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#750535}

chrome/browser/nfc/nfc_permission_context_unittest.cc

@@ -190,7 +190,6 @@ bool NfcPermissionContextTests::HasActivePrompt(
 
 void NfcPermissionContextTests::AcceptPrompt() {
   return AcceptPrompt(web_contents());
-  base::RunLoop().RunUntilIdle();
 }
 
 void NfcPermissionContextTests::AcceptPrompt(