Fix flaky xssAuditor test.

The layout test: object-src-inject.html is flaky.
Sometimes, this line is printed:
```
   CONSOLE MESSAGE: Blink Test Plugin: initializing
```

It is fired from BlinkTestInstance::Init(...);

It is racing with the end of the layout test.
This CL disables console error dump to avoid this issue.

Bug: 862959, 831155
Change-Id: I912e71b9ff8b7b5ccd7a4716f111f2017493e37a
Reviewed-on: https://chromium-review.googlesource.com/1135003
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Commit-Queue: Arthur Sonzogni <arthursonzogni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578994}
1 file changed