Add a partial load test for an animated PNG image

third_party/WebKit/LayoutTests/TestExpectations

 # Intentional failures to test the layout test system.
 Bug(intentional) harness-tests/crash.html [ Crash ]
 Bug(intentional) harness-tests/timeout.html [ Timeout ]
 
 # ====== Oilpan-only failures from here ======
 # Most of these actually cause the tests to report success, rather than
 # failure. Expected outputs will be adjusted for the better once Oilpan
 # has been well and truly enabled always.
 
 crbug.com/569901 crbug.com/24182 [ Debug ] jquery/manipulation.html [ Timeout Pass ]
@@ skipping 2560 matching lines @@
 crbug.com/701047 [ Mac10.12 ] editing/style/block-style-001.html [ Failure ]
 crbug.com/701047 [ Mac10.12 ] editing/style/block-style-002.html [ Failure ]
 crbug.com/701047 [ Mac10.12 ] editing/style/block-style-003.html [ Failure ]
 crbug.com/701047 [ Mac10.12 ] editing/style/block-styles-007.html [ Failure ]
 
 # mojo-loading: This is an experimental feature. failing virtual tests are
 # listed below.
 
 crbug.com/664873 http/tests/xmlhttprequest/small-chunks-response-text.html [ Failure Pass ]
 crbug.com/664873 virtual/mojo-loading/http/tests/xmlhttprequest/small-chunks-response-text.html [ Failure Pass ]
+crbug.com/700892 http/tests/images/png-animated-partial-load.html [ NeedsRebaseline ]
+crbug.com/700892 virtual/mojo-loading/http/tests/images/png-animated-partial-load.html [ NeedsRebaseline ]
 
 crbug.com/660295 inspector/elements/elements-panel-restore-selection-when-node-comes-later.html [ Pass Failure ]
 
 # [css-grid]
 crbug.com/659610 fast/css-grid-layout/grid-baseline.html [ Failure ]
 crbug.com/659610 fast/css-grid-layout/grid-baseline-margins.html [ Failure ]
 crbug.com/511177 external/csswg-test/css-grid-1/grid-layout-properties.html [ Failure ]
 
 # TODO(chrishall): this is a temporary mediation step as part of the P0 issue crbug.com/657646
 # this is not meant to be here for more than a few days (from 2016-11-03 SYD)
@@ skipping 238 matching lines @@
 crbug.com/700374 [ Win ] virtual/mojo-loading/http/tests/inspector/workers-on-navigation.html [ Failure Pass ]
 crbug.com/700374 [ Win ] http/tests/inspector/workers-on-navigation.html [ Failure Pass ]
 crbug.com/700387 [ Win7 ] external/wpt/fullscreen/api/document-exit-fullscreen-nested-in-iframe-manual.html [ Timeout Pass ]
 
 # Sheriff failures 2017-03-13
 crbug.com/701140 inspector-protocol/css/css-get-rule-list.html [ Failure Pass ]
 
 # Sheriff failures 2017-03-16
 crbug.com/701718 [ Win7 ] fast/table/border-collapsing/001-vertical.html [ Failure Pass ]
 crbug.com/701718 [ Win7 ] fast/table/border-collapsing/001.html [ Failure Pass ]