[Flaky][Linux] Mark decode-resize.js as flaky

This is a known issue but the expectation was (as assumed) missing in
this file: https://crrev.com/c/1074907

TBR=caseq@chromium.org

Bug: 847114
Change-Id: I94ea44f67d95b0aee83745980a3b221dec79b677
Reviewed-on: https://chromium-review.googlesource.com/1179759Reviewed-by: Friedrich Horschig <fhorschig@chromium.org>
Commit-Queue: Friedrich Horschig <fhorschig@chromium.org>
Cr-Commit-Position: refs/heads/master@{#584054}

third_party/WebKit/LayoutTests/LeakExpectations

@@ -82,6 +82,9 @@ crbug.com/862029 [ Linux ] http/tests/devtools/tracing/timeline-misc/timeline-wi
 # Sheriff 2018-08-15
 crbug.com/874442 [ Linux ] svg/animations/mpath-remove-from-dependents-on-delete-crash.html [ Pass Crash ]
 
+# Sheriff 2018-08-17
+crbug.com/847114 [ Linux ] http/tests/devtools/tracing/decode-resize.js [ Pass Failure ]
+
 ###########################################################################
 # WARNING: Memory leaks must be fixed asap. Sheriff is expected to revert #
 # culprit CLs instead of suppressing the leaks. If you have any question, #