Clean up test expectations after r237942

[Ryan Haddad]

The following tests are failing on High Sierra WK1 after https://trac.webkit.org/changeset/237942/webkit:

compositing/repaint/iframes/composited-iframe-with-fixed-background-doc-repaint.html
compositing/repaint/iframes/compositing-iframe-scroll-repaint.html
compositing/repaint/iframes/compositing-iframe-with-fixed-background-doc-repaint.html

--- /Volumes/Data/slave/highsierra-release-tests-wk1/build/layout-test-results/compositing/repaint/iframes/composited-iframe-with-fixed-background-doc-repaint-expected.txt
+++ /Volumes/Data/slave/highsierra-release-tests-wk1/build/layout-test-results/compositing/repaint/iframes/composited-iframe-with-fixed-background-doc-repaint-actual.txt
@@ -14,6 +14,8 @@
           (drawsContent 1)
           (repaint rects
             (rect 16.00 16.00 400.00 300.00)
+            (rect 24.00 16.00 100.00 8.00)
+            (rect 16.00 16.00 400.00 300.00)
           )
         )
         (GraphicsLayer

--- /Volumes/Data/slave/highsierra-release-tests-wk1/build/layout-test-results/compositing/repaint/iframes/compositing-iframe-scroll-repaint-expected.txt
+++ /Volumes/Data/slave/highsierra-release-tests-wk1/build/layout-test-results/compositing/repaint/iframes/compositing-iframe-scroll-repaint-actual.txt
@@ -13,6 +13,7 @@
           (bounds 432.00 332.00)
           (drawsContent 1)
           (repaint rects
+            (rect 16.00 16.00 400.00 300.00)
             (rect 16.00 16.00 400.00 300.00)
           )
           (children 1

--- /Volumes/Data/slave/highsierra-release-tests-wk1/build/layout-test-results/compositing/repaint/iframes/compositing-iframe-with-fixed-background-doc-repaint-expected.txt
+++ /Volumes/Data/slave/highsierra-release-tests-wk1/build/layout-test-results/compositing/repaint/iframes/compositing-iframe-with-fixed-background-doc-repaint-actual.txt
@@ -13,6 +13,7 @@
           (bounds 432.00 332.00)
           (drawsContent 1)
           (repaint rects
+            (rect 16.00 16.00 400.00 300.00)
             (rect 16.00 16.00 400.00 300.00)
           )
           (children 1

[Ryan Haddad]

Additional datapoints after r237942:

This test went from flaky failure -> failure on Mojave
compositing/repaint/iframes/composited-iframe-with-fixed-background-doc-repaint.html
https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=compositing%2Frepaint%2Fiframes%2Fcomposited-iframe-with-fixed-background-doc-repaint.html

This test went from flaky failure -> passing on Mojave
compositing/repaint/iframes/compositing-iframe-scroll-repaint.html
https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=compositing%2Frepaint%2Fiframes%2Fcompositing-iframe-scroll-repaint.html

This test went from flaky failure -> passing on Mojave
compositing/repaint/iframes/compositing-iframe-with-fixed-background-doc-repaint.html
https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=compositing%2Frepaint%2Fiframes%2Fcompositing-iframe-with-fixed-background-doc-repaint.html

[Simon Fraser (smfr)]

We should add High Sierra-specific results. Some of these repaints are triggered by AppKit, which differs between OS versions.

[Ryan Haddad]

https://trac.webkit.org/changeset/238013/webkit

[Radar WebKit Bug Importer]

<rdar://problem/45931139>