Add leak expectation for external/wpt/.../module/import-subgraph-404.html.

TBR=hiroshige
TBR_REASON=Sheriffing/gardening leak builder
BUG=724818

Review-Url: https://codereview.chromium.org/2895053002
Cr-Commit-Position: refs/heads/master@{#473449}

third_party/WebKit/LayoutTests/LeakExpectations

@@ -138,13 +138,14 @@ crbug.com/672740 virtual/mojo-loading/http/tests/security/mixedContent/websocket
 crbug.com/672740 http/tests/security/mixedContent/websocket/insecure-websocket-in-secure-page-worker.html [ Leak Pass ]
 crbug.com/672740 virtual/mojo-loading/http/tests/security/mixedContent/websocket/insecure-websocket-in-secure-page-worker.html [ Leak Pass ]
 
-# Flaky crashes, but bot build logs do not show the failure, at least as linked by the flakiness
-# board.
+# Flaky crashes, but bot build logs do not show the failure, at least
+# as linked by the flakiness dashboard.
 crbug.com/674858 [ Linux ] virtual/threaded/printing/offscreencanvas-2d-printing.html [ Pass Crash ]
 crbug.com/674858 [ Linux ] virtual/threaded/printing/offscreencanvas-webgl-printing.html [ Pass Crash ]
 
 # Sheriff: Commit causing leak found but non-trivial to revert
 crbug.com/718114 [ Linux ] external/wpt/html/semantics/scripting-1/the-script-element/module/crossorigin.html [ Leak Failure ]
+crbug.com/724818 [ Linux ] external/wpt/html/semantics/scripting-1/the-script-element/module/import-subgraph-404.html [ Leak Failure ]
 
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 # WARNING: Memory leaks must be fixed asap. Sheriff is expected to revert #