Temporarily disable web test for an upcoming DevTools change

The CL https://crrev.com/c/2096712 removes side-effect checking of
JavaScript snippets from the DevTools frontend and lets V8 handle the
side-effect checking.

This CL disables a test that incorrectly allows completion suggestions
for iframes, which is actually not guaranteed to be side-effect free
at the moment. After the above CL landed, this test needs to be
rebaselined and re-enabled.

R=petermarshall@chromium.org

Bug: chromium:1031243
Change-Id: I9de94a78f717ce54530b0e43f8121a30303554a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2096683
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749168}

third_party/blink/web_tests/TestExpectations

@@ -2389,6 +2389,9 @@ crbug.com/1032016 virtual/threaded/http/tests/devtools/tracing/timeline-js/timel
 crbug.com/1032016 http/tests/devtools/bindings/inline-styles-binding.js [ Pass Failure ]
 crbug.com/1032016 http/tests/devtools/bindings/livelocation-main-frame-navigated.js [ Pass Failure ]
 
+# Temporarily disabled so we can land a frontend change that removes side-effect handling in the frontend.
+crbug.com/1031243 http/tests/devtools/console-cd-completions.js [ Pass Failure ]
+
 # We only want to run one of the web-animations-api tests in stable mode.
 crbug.com/441553 virtual/stable/web-animations-api/* [ Skip ]
 # These tests *only* run in stable, to verify that these features are unsupported and throw exceptions.