Investigate ServerProcess Crash in blink_web_tests

There was a flaky failure in vulkan_native_blink_web_tests which would lead to
the test runner itself crashing.

Somehow when parsing input the results from re.match() the first result is a
NoneType, leading to a failure when adding group(1) + group(2)

I can't reproduce locally, so I want to add logging for this case.

TEST=vulkan_native_blink_web_tests

Bug: 1021563
Change-Id: I1cdec431ebc08df4a891c1062c3f1c64c80bc826
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2003029Reviewed-by: Robert Ma <robertma@chromium.org>
Commit-Queue: Jonathan Ross <jonross@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732825}

third_party/blink/tools/blinkpy/web_tests/port/server_process.py

@@ -66,6 +66,10 @@ def quote_data(data):
     for l in txt.splitlines():
         m = _trailing_spaces_re.match(l)
         if m:
+            # TODO(crbug.com/1021563): Remove this once we can determine why
+            # bots are occasionally crashing with a NoneType + str error.
+            if m.group(1) is None:
+                logging.error(l)
             l = m.group(1) + m.group(2).replace(' ', '\x20')
         lines.append(l)
     return lines

third_party/blink/web_tests/FlagExpectations/use-vulkan=native

@@ -25,9 +25,6 @@ crbug.com/1002547 fast/canvas/imagebitmap/transferFromImageBitmap-alpha.html [ S
 crbug.com/1002547 fast/canvas/imagebitmap/transferFromImageBitmap-no-alpha.html [ Skip ]
 crbug.com/1002547 fast/canvas/imagebitmap/transferFromImageBitmap.html [ Skip ]
 
-# Crashing third_party/blink/tools/blinkpy/common/message_pool.py
-crbug.com/1018884 compositing/overflow/scrollbar-layer-placement.html [ Skip ]
-
 # OOPIF tests fail due to input event coordinates.
 crbug.com/935970 http/tests/misc/scroll-cross-origin-iframes-scrollbar.html [ Skip ]
 crbug.com/935970 http/tests/security/referrer-policy-redirect-link.html [ Skip ]