Bug 1467030 [wpt PR 11361] - Add an API to query whether the window h…

…as seen a user gesture., a=testonly

Automatic update from web-platform-testsAdd an API to query whether the window has seen a user gesture.

Add a variable on the navigator object to query whether the frame has
seen a user activation ever.

The postMessage part of the proposal will be done in a separate patch,
this change is limited to just adding the object definition and
exposing it on navigator.

https://github.com/dtapuska/useractivation
whatwg/html#1983

BUG=846858

Change-Id: I6ca4c80f4096bfae9ca13b175b46df6b4486a6dd
Reviewed-on: https://chromium-review.googlesource.com/1076979
Commit-Queue: Dave Tapuska <dtapuskachromium.org>
Reviewed-by: Rick Byers <rbyerschromium.org>
Reviewed-by: Mustaq Ahmed <mustaqchromium.org>
Cr-Commit-Position: refs/heads/master{#572847}

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wpt-commits: dfca5197519caef6c189636b5d80b33e3424e91e
wpt-pr: 11361

UltraBlame original commit: 6ca48fa9e7f0348e0c84196f401467f3afcc5835