[Bindings] Create and use V8 context snapshots

third_party/WebKit/LayoutTests/SlowTests

Index: third_party/WebKit/LayoutTests/SlowTests
diff --git a/third_party/WebKit/LayoutTests/SlowTests b/third_party/WebKit/LayoutTests/SlowTests
index 88871bfac50b2db9c313b382e695f0ba4588e31e..0943c6461c5de9edb2c8ad92cb397503b03c5f5a 100644
--- a/third_party/WebKit/LayoutTests/SlowTests
+++ b/third_party/WebKit/LayoutTests/SlowTests
@@ -386,3 +386,9 @@ crbug.com/722825 media/controls/video-enter-exit-fullscreen-while-hovering-shows
 crbug.com/722825 media/controls/video-enter-exit-fullscreen-without-hovering-doesnt-show-controls.html [ Slow ]
 crbug.com/722825 virtual/new-remote-playback-pipeline/media/controls/video-enter-exit-fullscreen-while-hovering-shows-controls.html [ Slow ]
 crbug.com/722825 virtual/new-remote-playback-pipeline/media/controls/video-enter-exit-fullscreen-without-hovering-doesnt-show-controls.html [ Slow ]
+
+# When we enable snapshot feature, adding an external reference table makes isolate
+# creation slower, and these tests create too many isolates in a test.
+crbug.com/724496 virtual/off-main-thread-fetch/external/wpt/service-workers/service-worker/register-link-element.https.html [ Slow ]
+crbug.com/724496 external/wpt/service-workers/service-worker/register-link-element.https.html [ Slow ]
+crbug.com/724496 external/wpt/service-workers/service-worker/registration.https.html [ Slow ]