Create Wptrunner config files on the fly

As changing CWD breaks MSAN builder, this change tries to use absolute
path in config files, which in turn requires the config files to be
created at run time

Bug: 360008882, 359319433
Cq-Include-Trybots: luci.chromium.try:linux-webkit-msan-rel
Change-Id: I657ea10ca7b30afec764097a4d281968ff2964af
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5918050
Reviewed-by: Dirk Pranke <[email protected]>
Commit-Queue: Weizhong Xia <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1367901}
diff --git a/BUILD.gn b/BUILD.gn
index 7c46b25..3d8fa4d 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -1297,7 +1297,7 @@
       "//testing/scripts/run_isolated_script_test.py",
       "//testing/xvfb.py",
       "//third_party/blink/tools/",
-      "//third_party/blink/web_tests/external/wpt/config.json",
+      "//third_party/blink/web_tests/external/wpt/.config.json",
       "//third_party/blink/web_tests/resources/",
       "//third_party/blink/web_tests/TestLists/",
       "//third_party/pywebsocket3/src/mod_pywebsocket/",