HTML: review followup (web-platform-tests#12662)

Follow up to review comments in
web-platform-tests#12636.

RTCIceTransport: start() implementation.

This change implements the RTCIceTransport.start() method and
associated methods/events: addRemoteCandidate(), getRemoteCandidates(),
role, onstatechange.

Bug: 864871
Change-Id: Ic6ac7ce4c9ba98b1dc2610ed7847e6b9714f6c8d
Reviewed-on: https://chromium-review.googlesource.com/1161605
Commit-Queue: Steve Anton <steveanton@chromium.org>
Reviewed-by: Harald Alvestrand <hta@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585915}

Handle ManifestVersionMismatch when loading the test manifest, a=test…

…only

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1485403
gecko-commit: 4f8e3acdef35337054c23776fcb78ce518927fc3
gecko-integration-branch: mozilla-inbound
gecko-reviewers: testonly

[HTTP/2.0][WIP] H2 server documentation (web-platform-tests#12655)

Added documentation for H2ResponseWriter API as well as a more general Handler explanation and how to use new functionality

Migrate linter exception for PRINT STATEMENT to match new location.

Fullscreen elements that were root level elements weren't sized prope…

…rly.

Avoid setting position absolute on top layer elements that are the
documentElement. This matches what Firefox does.

The root element is special when it is in fullscreen mode because it does
not get the style applied that forces its dimensions and position to be
fixed.

BUG=876339

Change-Id: I42b18047dc9648585bc279510d66decd6d6a4516
Reviewed-on: https://chromium-review.googlesource.com/1186961
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585830}

HTML: test dynamically updating the text content of a legend

[BackgroundFetch] Part 1: Remove BackgroundFetchSettledFetches.

This removes BackgroundFetchSettledFetches from blink, idl files,
and the WPT tests.

In a follow up CL I'll remove it from all the event dispatcher code
on the browser side.

This fix also makes cache_query_params optional in MatchRequests() in mojo.
This is required because otherwise the mojo bindings logic crashes the renderer
when we try to pass in a nullptr for cache_query_params from blink.

Bug: 869918, 863016
Change-Id: Ifa933451f98f82902d8455ba5401c629c8c24811
Reviewed-on: https://chromium-review.googlesource.com/1186735
Commit-Queue: Mugdha Lakhani <nator@chromium.org>
Reviewed-by: Peter Beverloo <peter@chromium.org>
Reviewed-by: Rayan Kanso <rayankans@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585847}

Avoid overflowing snap areas in scrollTo wpt tests

Some tests in scrollTo-scrollBy-snaps.html are failing on wpt dashboard.
This is caused by the uncertainty of the window size for testharness
tests. If the window size becomes small enough that the snap area covers
the snapport, the expected snap position is ignored because any scroll
position is considered a valid snap position. This patch changes the
landing position of scrollTo and scrollBy for failing cases so that the
snap area does not cover ths snapport regardless of the window size.

More specifically, the snap area's vertical and horizontal dimensions
are 600px each thus covering the [1000, 1600] range with expected snap
position at 1000. Previously if the test vertically scrolled to 1200 and
the window's size is smaller than 400, the snap area will cover the
window. Now the test scrolls to 900 (100px before the snap position),
ensuring that the target snap area won't cover the window regardless of
the size.

Bug: 876052
Change-Id: I448ecb1e3cc2cc458d467472ca38d49bf01d2901
Reviewed-on: https://chromium-review.googlesource.com/1182299
Commit-Queue: Sandra Sun <sunyunjia@chromium.org>
Reviewed-by: Majid Valipour <majidvp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585926}

Fetch/XHR/Beacon: test locked/disturbed ReadableStream

See whatwg/fetch#801 for context.