[WPE][WebRTC] Support b/f cache of connected peer connections

[Lauro Moura]

These two tests have been failing rather consistently (dozens of failures between rare passes) since their introduction in r252889.

* webrtc/peerconnection-page-cache-long.html
* webrtc/peerconnection-page-cache.html

For the last one, the assertion fails when coming back to load the initial page from the cache (in the `pageshow` event).

[Diego Pino]

The tests are passing for GTK since r261277 (webrtc/peerconnection-page-cache.html) and r261343 (webrtc/peerconnection-page-cache-long.html).

However, in WPE webrtc/peerconnection-page-cache.html is flaky and webrtc/peerconnection-page-cache-long.html is still failing.

Removed failures from GTK and updated expectations for WPE:

  webrtc/peerconnection-page-cache-long.html [ Failure ]
  webrtc/peerconnection-page-cache.html [ Failure Pass ]

[Diego Pino]

webrtc/peerconnection-page-cache-long.html started to fail again in GTK since [r261409-r261417]

[Diego Pino]

peerconnection-page-cache.html is flaky.

Diff: https://build.webkit.org/results/GTK%20Linux%2064-bit%20Release%20(Tests)/r261492%20(13697)/webrtc/peerconnection-page-cache-diff.txt

--- /home/slave/webkitgtk/gtk-linux-64-release-tests/build/layout-test-results/webrtc/peerconnection-page-cache-expected.txt
+++ /home/slave/webkitgtk/gtk-linux-64-release-tests/build/layout-test-results/webrtc/peerconnection-page-cache-actual.txt
@@ -1,4 +1,4 @@
 
 
-PASS peerconnection-page-cache 
+FAIL peerconnection-page-cache assert_equals: expected "connected" but got "connecting"
 

Stderr: https://build.webkit.org/results/GTK%20Linux%2064-bit%20Release%20(Tests)/r261492%20(13697)/webrtc/peerconnection-page-cache-stderr.txt

(webrtc_video_engine.cc:3160): Absent receive stream; ignoring clearing encoded frame sink for ssrc 0

[Diego Pino]

The was only one test filed under this bug:

  webrtc/peerconnection-page-cache-long.html [ Failure Pass Timeout ]

The test has been constantly passing for the last 1000 revisions:

https://results.webkit.org/?limit=1000&platform=GTK&platform=WPE&suite=layout-tests&test=webrtc%2Fpeerconnection-page-cache-long.html

Marking bug as resolved.

Test removed from test expectations in r287490.