[Benchmarking] Disable flaky blink perf tests

Disabling the following flaky tests on android-pixel2_webview-perf:
* blink_perf.css/SelectorCountScaling.html
* blink_perf.dom/custom-element-default-style-with-shadow.html
* blink_perf.dom/custom-element-default-style.html
* blink_perf.layout/ruby.html
* blink_perf.layout/chapter-reflow-once.html
* blink_perf.layout/flexbox-row-stretch-height-indefinite.html
* blink_perf.layout/ArabicLineLayout.html
* blink_perf.parser/innerHTML-setter-siblings.html

TBR=wenbinzhang@google.com
NOTRY=true

Bug: 1142315
Change-Id: I88a598703b6d1e8bf0c8d96d380cb7b01ca685d6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2503823Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: John Chen <johnchen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#821466}

tools/perf/expectations.config

@@ -38,6 +38,11 @@ crbug.com/1128019 [ android-nexus-5x ] blink_perf.bindings/worker-structured-clo
 
 # Benchmark: blink_perf.css
 crbug.com/891878 [ android-nexus-5x android-webview ] blink_perf.css/CustomPropertiesVarAlias.html [ Skip ]
+crbug.com/1142315 [ android-pixel-2 android-webview ] blink_perf.css/SelectorCountScaling.html [ Skip ]
+
+# Benchmark: blink_perf.dom
+crbug.com/1142315 [ android-pixel-2 android-webview ] blink_perf.dom/custom-element-default-style.html [ Skip ]
+crbug.com/1142315 [ android-pixel-2 android-webview ] blink_perf.dom/custom-element-default-style-with-shadow.html [ Skip ]
 
 # Benchmark: blink_perf.events
 crbug.com/963945 [ android-nexus-5x android-webview ] blink_perf.events/EventsDispatchingInDeeplyNestedV1ShadowTrees.html [ Skip ]
@@ -51,6 +56,10 @@ crbug.com/832686 [ android-nexus-5 ] blink_perf.layout/subtree-detaching.html [
 crbug.com/910207 [ android-nexus-5x ] blink_perf.layout/subtree-detaching.html [ Skip ]
 crbug.com/966921 [ android ] blink_perf.layout/line-layout-fit-content.html [ Skip ]
 crbug.com/966921 [ android ] blink_perf.layout/line-layout-fit-content-break-word.html [ Skip ]
+crbug.com/1142315 [ android-pixel-2 android-webview ] blink_perf.layout/ruby.html [ Skip ]
+crbug.com/1142315 [ android-pixel-2 android-webview ] blink_perf.layout/chapter-reflow-once.html [ Skip ]
+crbug.com/1142315 [ android-pixel-2 android-webview ] blink_perf.layout/flexbox-row-stretch-height-indefinite.html [ Skip ]
+crbug.com/1142315 [ android-pixel-2 android-webview ] blink_perf.layout/ArabicLineLayout.html [ Skip ]
 
 # Benchmark: blink_perf.owp_storage
 crbug.com/1128019 [ android-pixel-2 ] blink_perf.owp_storage/idb-load-docs.html [ Skip ]
@@ -75,6 +84,7 @@ crbug.com/966913 [ android-nexus-5x android-webview ] blink_perf.parser/query-se
 crbug.com/966613 [ android-pixel-2 ] blink_perf.parser/query-selector-all-class-deep.html [ Skip ]
 crbug.com/966613 [ android-pixel-2 ] blink_perf.parser/query-selector-all-deep.html [ Skip ]
 crbug.com/966613 [ android-pixel-2 ] blink_perf.parser/query-selector-all-id-deep.html [ Skip ]
+crbug.com/1142315 [ android-pixel-2 android-webview ] blink_perf.parser/innerHTML-setter-siblings.html [ Skip ]
 
 # Benchmark: blink_perf.shadow_dom
 crbug.com/702319 [ android-nexus-5x ] blink_perf.shadow_dom/* [ Skip ]