Change EditingNG to experimental from test"

This reverts commit c00ca060.

Reason for revert: EditingNG is ready on Canary.

Original change's description:
> Change EditingNG from experimental to test
>
> This patch changes runtime enabled feature EditingNG from experimental
> to test to avoid users who turn on "Experimental Web Platform features"
> not to hit EditingNG issues.
>
> Bug: 707656, 1125477
> Change-Id: I81b56ff56c44da74b0702e4e2f2d81355a0a0c2e
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2437834
> Commit-Queue: Koji Ishii <kojii@chromium.org>
> Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
> Reviewed-by: Koji Ishii <kojii@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#812020}

TBR=yosin@chromium.org,tkent@chromium.org,kojii@chromium.org,ikilpatrick@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 707656
Bug: 1125477
Change-Id: Idd23638d2d3c028d3452f237c35288915154691a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2463045Reviewed-by: Koji Ishii <kojii@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Auto-Submit: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815520}

content/test/data/accessibility/html/contenteditable-descendants-expected-auralinux.txt

@@ -15,7 +15,8 @@
 ++++++++++[static] name='Always expose editable tables as tables.' editable
 ++++[list] editable
 ++++++[list item] editable
-++++++++[static] name='1. ' editable
+++++++++[panel] editable
+++++++++++[static] name='1. '
 ++++++++[static] name='Editable list item.' editable
 ++[paragraph]
 ++++[static] name='Non-editable paragraph.'

content/test/data/accessibility/html/contenteditable-descendants-expected-blink.txt

@@ -26,6 +26,8 @@ rootWebArea
 ++++++++list editable richlyEditable
 ++++++++++listItem editable richlyEditable
 ++++++++++++listMarker editable richlyEditable name='1. '
+++++++++++++++staticText name='1. '
+++++++++++++++++inlineTextBox name='1. '
 ++++++++++++staticText editable richlyEditable name='Editable list item.'
 ++++++++++++++inlineTextBox name='Editable list item.'
 ++++++paragraph

content/test/data/accessibility/html/contenteditable-descendants-expected-uia-win.txt

@@ -15,7 +15,8 @@ Document
 ++++++++++Text Name='Always expose editable tables as tables.' IsControlElement=false
 ++++List
 ++++++ListItem
-++++++++Text Name='1. ' IsControlElement=false
+++++++++Group
+++++++++++Text Name='1. ' IsControlElement=false
 ++++++++Text Name='Editable list item.' IsControlElement=false
 ++Group IsControlElement=false
 ++++Text Name='Non-editable paragraph.'

content/test/data/accessibility/html/contenteditable-descendants-expected-win.txt

@@ -14,8 +14,9 @@ ROLE_SYSTEM_DOCUMENT READONLY FOCUSABLE ia2_hypertext='<obj0><obj1><obj2>' n_sel
 ++++++++ROLE_SYSTEM_CELL name='Always expose editable tables as tables.' IA2_STATE_EDITABLE ia2_hypertext='Always expose editable tables as tables.' n_selections=0
 ++++++++++ROLE_SYSTEM_STATICTEXT name='Always expose editable tables as tables.' IA2_STATE_EDITABLE ia2_hypertext='Always expose editable tables as tables.' n_selections=0
 ++++ROLE_SYSTEM_LIST IA2_STATE_EDITABLE ia2_hypertext='<obj0>' n_selections=0
-++++++ROLE_SYSTEM_LISTITEM IA2_STATE_EDITABLE ia2_hypertext='1. Editable list item.' n_selections=0
-++++++++ROLE_SYSTEM_STATICTEXT name='1. ' IA2_STATE_EDITABLE ia2_hypertext='1. ' n_selections=0
+++++++ROLE_SYSTEM_LISTITEM IA2_STATE_EDITABLE ia2_hypertext='<obj0>Editable list item.' n_selections=0
+++++++++ROLE_SYSTEM_GROUPING IA2_STATE_EDITABLE ia2_hypertext='1. ' n_selections=0
+++++++++++ROLE_SYSTEM_STATICTEXT name='1. ' ia2_hypertext='1. ' n_selections=0
 ++++++++ROLE_SYSTEM_STATICTEXT name='Editable list item.' IA2_STATE_EDITABLE ia2_hypertext='Editable list item.' n_selections=0
 ++IA2_ROLE_PARAGRAPH ia2_hypertext='Non-editable paragraph.' n_selections=0
 ++++ROLE_SYSTEM_STATICTEXT name='Non-editable paragraph.' ia2_hypertext='Non-editable paragraph.' n_selections=0

content/test/data/accessibility/html/contenteditable-descendants-with-selection-expected-auralinux.txt

@@ -15,5 +15,6 @@
 ++++++++++[static] name='Always expose editable tables as tables.' editable selection_start=0 selection_end=3
 ++++[list] editable selection_start=0 selection_end=3
 ++++++[list item] editable selection_start=0 selection_end=3
-++++++++[static] name='1. ' editable selection_start=0 selection_end=3
+++++++++[panel] editable selection_start=0 selection_end=3
+++++++++++[static] name='1. ' selection_start=0 selection_end=3
 ++++++++[static] name='Editable list item.' editable selection_start=0 selection_end=3

content/test/data/accessibility/html/contenteditable-descendants-with-selection-expected-blink.txt

@@ -26,5 +26,7 @@ rootWebArea
 ++++++++list editable richlyEditable
 ++++++++++listItem editable richlyEditable
 ++++++++++++listMarker editable richlyEditable name='1. '
+++++++++++++++staticText name='1. '
+++++++++++++++++inlineTextBox name='1. '
 ++++++++++++staticText editable richlyEditable name='Editable list item.'
 ++++++++++++++inlineTextBox name='Editable list item.'

content/test/data/accessibility/html/contenteditable-descendants-with-selection-expected-uia-win.txt

@@ -15,5 +15,6 @@ Document
 ++++++++++Text Name='Always expose editable tables as tables.' IsControlElement=false
 ++++List
 ++++++ListItem
-++++++++Text Name='1. ' IsControlElement=false
+++++++++Group
+++++++++++Text Name='1. ' IsControlElement=false
 ++++++++Text Name='Editable list item.' IsControlElement=false

content/test/data/accessibility/html/contenteditable-descendants-with-selection-expected-win.txt

@@ -14,6 +14,7 @@ ROLE_SYSTEM_DOCUMENT READONLY FOCUSABLE ia2_hypertext='<obj0>' caret_offset=1 n_
 ++++++++ROLE_SYSTEM_CELL name='Always expose editable tables as tables.' IA2_STATE_EDITABLE ia2_hypertext='Always expose editable tables as tables.' n_selections=1 selection_start=0 selection_end=3
 ++++++++++ROLE_SYSTEM_STATICTEXT name='Always expose editable tables as tables.' IA2_STATE_EDITABLE ia2_hypertext='Always expose editable tables as tables.' n_selections=1 selection_start=0 selection_end=3
 ++++ROLE_SYSTEM_LIST IA2_STATE_EDITABLE ia2_hypertext='<obj0>' n_selections=1 selection_start=0 selection_end=3
-++++++ROLE_SYSTEM_LISTITEM IA2_STATE_EDITABLE ia2_hypertext='1. Editable list item.' n_selections=1 selection_start=0 selection_end=3
-++++++++ROLE_SYSTEM_STATICTEXT name='1. ' IA2_STATE_EDITABLE ia2_hypertext='1. ' n_selections=1 selection_start=0 selection_end=3
+++++++ROLE_SYSTEM_LISTITEM IA2_STATE_EDITABLE ia2_hypertext='<obj0>Editable list item.' n_selections=1 selection_start=0 selection_end=3
+++++++++ROLE_SYSTEM_GROUPING IA2_STATE_EDITABLE ia2_hypertext='1. ' n_selections=1 selection_start=0 selection_end=3
+++++++++++ROLE_SYSTEM_STATICTEXT name='1. ' ia2_hypertext='1. ' n_selections=1 selection_start=0 selection_end=3
 ++++++++ROLE_SYSTEM_STATICTEXT name='Editable list item.' IA2_STATE_EDITABLE ia2_hypertext='Editable list item.' n_selections=1 selection_start=0 selection_end=3

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -713,7 +713,7 @@
     {
       // http://crbug.com/707656 content editable in LayoutNG.
       name: "EditingNG",
-      status: "test",
+      status: "experimental",
     },
     {
       name: "EncryptedMediaEncryptionSchemeQuery",