[tools/perf] Disable failing blink_perf.bindings stories in Pixel 2

These are the only two stories still often failing on
android-pixel2-perf bot.

NOTRY=true
TBR=nednguyen@google.com

Bug: 865400
Change-Id: I3439893506c11b92d0d18a337ec7eef43c55080b
Reviewed-on: https://chromium-review.googlesource.com/c/1344133Reviewed-by: Juan Antonio Navarro Pérez <perezju@chromium.org>
Commit-Queue: Juan Antonio Navarro Pérez <perezju@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609699}

tools/perf/expectations.config

@@ -19,7 +19,8 @@ crbug.com/882881 [ Nexus_5 ] blink_perf.bindings/worker-structured-clone-json-to
 crbug.com/882881 [ Nexus_5X ] blink_perf.bindings/worker-structured-clone-json-to-worker.html [ Skip ]
 crbug.com/882881 [ Nexus_5 ] blink_perf.bindings/worker-structured-clone-json-from-worker.html [ Skip ]
 crbug.com/882881 [ Nexus_5X ] blink_perf.bindings/worker-structured-clone-json-from-worker.html [ Skip ]
-
+crbug.com/865400 [ Pixel_2 ] blink_perf.bindings/structured-clone-long-string-deserialize.html [ Skip ]
+crbug.com/865400 [ Pixel_2 ] blink_perf.bindings/structured-clone-long-string-serialize.html [ Skip ]
 
 # Benchmark: blink_perf.canvas
 crbug.com/593973 [ Android_Svelte ] blink_perf.canvas/* [ Skip ]