Add webrtc_apprtc_browsertest.cc resource dir to .gitignore.

No-Try: True
Bug: chromium:997673
Change-Id: Ic0578fad31c011534bd5ebd876f45e737b2badb7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/151128
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#29044}
diff --git a/.gitignore b/.gitignore
index 7de75c9..0dff6f4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -64,6 +64,7 @@
 /rtc_tools/testing/*.gz
 /rtc_tools/testing/golang/*/*.gz
 /rtc_tools/testing/golang/*/*.zip
+/rtc_tools/testing/webrtc_apprtc_browsertest/*
 /x86-generic_out/
 /xcodebuild
 /.vscode