Begin importing WPT runner codebase into Chromium.

This code is used to run WPT tests in the public upstream repository,
and is being integrated into Chromium CI.

This change begins the automatic import of this code, as well as adding
several lint and presubmit check exclusions.

Bug: 937369
Change-Id: Ie9409e671b0c06a10bb509a53946687c0b7a3f65
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1495372
Reviewed-by: Dirk Pranke <[email protected]>
Reviewed-by: Lei Zhang <[email protected]>
Reviewed-by: Robert Ma <[email protected]>
Commit-Queue: Luke Z <[email protected]>
Cr-Commit-Position: refs/heads/master@{#637373}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index fcc8432..59aaaad 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -1378,7 +1378,7 @@
   pattern = input_api.re.compile('^(?:<<<<<<<|>>>>>>>) |^=======$')
   errors = []
   for line_num, line in f.ChangedContents():
-    if f.LocalPath().endswith('.md'):
+    if f.LocalPath().endswith(('.md', '.rst', '.txt')):
       # First-level headers in markdown look a lot like version control
       # conflict markers. http://daringfireball.net/projects/markdown/basics
       continue