Remove UserScript support, which is not used by Chromium

LayoutTests/platform/chromium/TestExpectations

 # These are the layout test expectations for the Chromium port(s) of WebKit.
 #
 # See http://trac.webkit.org/wiki/TestExpectations for more information on this file.
 
 # -----------------------------------------------------------------
 # SLOW TESTS
 # -----------------------------------------------------------------
 
 crbug.com/24182 [ Debug ] css3/flexbox/multiline-justify-content.html [ Slow ]
 webkit.org/b/91666 [ Mac ] editing/input/emacs-ctrl-o.html [ Failure Slow ]
@@ skipping 1878 matching lines @@
 webkit.org/b/44199 webkit.org/b/63057 [ Release ] perf/array-binary-search.html [ Failure Pass Slow ]
 webkit.org/b/44199 [ Release ] perf/array-reverse.html [ Pass Timeout ]
 webkit.org/b/63057 [ Release ] perf/adding-radio-buttons.html [ Failure Pass ]
 webkit.org/b/96977 [ Mac Release ] perf/nested-combined-selectors.html [ Failure Pass ]
 
 # Failing after http://trac.webkit.org/changeset/65665/
 
 # new or failing since WebKit rev. 65740:65800
 crbug.com/53073 [ Debug ] storage/websql/change-version.html
 
-# r66144 added tests to test user scripts on special documents, and Linux can't
-# pass them because they rely on QuickTime being installed. We wontfix these
-# tests and let the Mac/Win coverage ensure that the (cross-platform)
-# special-document machinery still works.
-crbug.com/53546 [ Linux ] userscripts/user-script-video-document.html [ WontFix ]
-
 # Requires page cache.
 webkit.org/b/45652 fast/viewport/viewport-128.html [ Timeout ]
 
 webkit.org/b/45737 [ Win Linux Mac Debug ] fast/frames/frame-limit.html [ Timeout ]
 webkit.org/b/45737 [ Win Linux Release ] fast/frames/frame-limit.html [ Slow ]
 
 # Regressions from webkit roll r67178:t67358
 webkit.org/b/60092 [ Debug ] fast/forms/select-set-length-with-mutation-remove.html [ Crash Pass Timeout ]
 webkit.org/b/60093 [ Linux Debug ] http/tests/incremental/slow-utf8-text.pl [ Slow ]
 
@@ skipping 1089 matching lines @@
 crbug.com/132898 http/tests/websocket/tests/hybi/workers/close.html [ Failure Pass ]
 
 webkit.org/b/96839 compositing/geometry/fixed-position-transform-composited-page-scale.html [ ImageOnlyFailure ]
 webkit.org/b/96839 virtual/softwarecompositing/geometry/fixed-position-transform-composited-page-scale.html [ ImageOnlyFailure ]
 webkit.org/b/96839 compositing/geometry/fixed-position-transform-composited-page-scale-down.html [ ImageOnlyFailure ]
 webkit.org/b/96839 virtual/softwarecompositing/geometry/fixed-position-transform-composited-page-scale-down.html [ ImageOnlyFailure ]
 webkit.org/b/89702 compositing/scaling/tiled-layer-recursion.html [ ImageOnlyFailure Pass ]
 webkit.org/b/89702 virtual/softwarecompositing/scaling/tiled-layer-recursion.html [ ImageOnlyFailure Pass ]
 
 webkit.org/b/89789 [ Mac ] plugins/embed-attributes-style.html [ ImageOnlyFailure Pass ]
-webkit.org/b/89789 [ XP ] userscripts/user-script-video-document.html [ Pass Timeout ]
 
 # Flaky
 webkit.org/b/89794 [ Mac ] fast/regions/get-regions-by-content2.html [ Crash Pass ]
 
 # Results are not useful and a bit indeterminate -- test needs help.
 webkit.org/b/92811 compositing/video-page-visibility.html [ Crash Failure ImageOnlyFailure ]
 webkit.org/b/92811 virtual/softwarecompositing/video-page-visibility.html [ Crash Failure ImageOnlyFailure ]
 
 # Flaky
 webkit.org/b/89812 [ Debug ] fast/parser/parser-yield-timing.html [ Failure Pass ]
@@ skipping 764 matching lines @@
 crbug.com/225883 [ Win Mac ] inspector/profiler/memory-instrumentation-external-array.html [ Failure ]
 
 crbug.com/229021 [ Mac ] inspector/styles/device-metrics-fit-window.html [ Failure ]
 crbug.com/229113 http/tests/history/redirect-js-location-assign-0-seconds.html [ Pass Failure ]
 crbug.com/229698 http/tests/security/mixedContent/about-blank-iframe-in-main-frame.html [ Pass Failure ]
 crbug.com/230079 [ Lion ] http/tests/css/vertical-align-baseline-after-image-load-2.html [ Pass ImageOnlyFailure ]
 crbug.com/230153 [ Debug ] svg/as-background-image/tiled-background-image.html [ Pass ImageOnlyFailure ]
 
 crbug.com/230315 fast/events/scale-and-scroll-window.html [ Pass ImageOnlyFailure ]
 crbug.com/230339 virtual/gpu/compositedscrolling/scrollbars/short-scrollbar.html [ Pass ImageOnlyFailure ]