DevTools: [CSS] remove CSS Regions experiment from DevTools.

Source/devtools/protocol.json

 {
     "version": { "major": "1", "minor": "1" },
     "domains": [{
         "domain": "Inspector",
         "hidden": true,
         "types": [],
         "commands": [
             {
                 "name": "enable",
                 "description": "Enables inspector domain notifications."
@@ skipping 2549 matching lines @@
                 "properties": [
                     { "name": "text", "type": "string", "description": "Media query text." },
                     { "name": "source", "type": "string", "enum": ["mediaRule", "importRule", "linkedSheet", "inlineSheet"], "description": "Source of the media query: \"mediaRule\" if specified by a @media rule, \"importRule\" if specified by an @import rule, \"linkedSheet\" if specified by a \"media\" attribute in a linked stylesheet's LINK tag, \"inlineSheet\" if specified by a \"media\" attribute in an inline stylesheet's STYLE tag." },
                     { "name": "sourceURL", "type": "string", "optional": true, "description": "URL of the document containing the media query description." },
                     { "name": "range", "$ref": "SourceRange", "optional": true, "description": "The associated rule (@media or @import) header range in the enclosing stylesheet (if available)." },
                     { "name": "parentStyleSheetId", "$ref": "StyleSheetId", "optional": true, "description": "Identifier of the stylesheet containing this object (if exists)." }
                 ],
                 "description": "CSS media query descriptor."
             },
             {
-                "id": "Region",
-                "type": "object",
-                "properties": [
-                    { "name": "regionOverset", "type": "string", "enum": ["overset", "fit", "empty"], "description": "The \"overset\" attribute of a Named Flow." },
-                    { "name": "nodeId", "$ref": "DOM.NodeId", "description": "The corresponding DOM node id." }
-                ],
-                "description": "This object represents a region that flows from a Named Flow.",
-                "hidden": true
-            },
-            {
-                "id": "NamedFlow",
-                "type": "object",
-                "properties": [
-                    { "name": "documentNodeId", "$ref": "DOM.NodeId", "description": "The document node id." },
-                    { "name": "name", "type": "string", "description": "Named Flow identifier." },
-                    { "name": "overset", "type": "boolean", "description": "The \"overset\" attribute of a Named Flow." },
-                    { "name": "content", "type": "array", "items": { "$ref": "DOM.NodeId" }, "description": "An array of nodes that flow into the Named Flow." },
-                    { "name": "regions", "type": "array", "items": { "$ref": "Region" }, "description": "An array of regions associated with the Named Flow." }
-                ],
-                "description": "This object represents a Named Flow.",
-                "hidden": true
-            },
-            {
                 "id": "PlatformFontUsage",
                 "type": "object",
                 "properties": [
                     { "name": "familyName", "type": "string", "description": "Font's family name reported by platform."},
                     { "name": "glyphCount", "type": "number", "description": "Amount of glyphs that were rendered with this font."}
                 ],
                 "description": "Information about amount of glyphs that were rendered with given font.",
                 "hidden": true
             }
         ],
@@ skipping 117 matching lines @@
                 ],
                 "description": "Creates a new empty rule with the given <code>selector</code> in a special \"inspector\" stylesheet in the owner document of the context node."
             },
             {
                 "name": "forcePseudoState",
                 "parameters": [
                     { "name": "nodeId", "$ref": "DOM.NodeId", "description": "The element id for which to force the pseudo state." },
                     { "name": "forcedPseudoClasses", "type": "array", "items": { "type": "string", "enum": ["active", "focus", "hover", "visited"] }, "description": "Element pseudo classes to force when computing the element's style." }
                 ],
                 "description": "Ensures that the given node will have specified pseudo-classes whenever its style is computed by the browser."
-            },
-            {
-                "name": "getNamedFlowCollection",
-                "parameters": [
-                    { "name": "documentNodeId", "$ref": "DOM.NodeId", "description": "The document node id for which to get the Named Flow Collection." }
-                ],
-                "returns": [
-                    { "name": "namedFlows", "type": "array", "items": { "$ref": "NamedFlow" }, "description": "An array containing the Named Flows in the document." }
-                ],
-                "description": "Returns the Named Flows from the document.",
-                "hidden": true
             }
         ],
         "events": [
             {
                 "name": "mediaQueryResultChanged",
                 "description": "Fires whenever a MediaQuery result changes (for example, after a browser window has been resized.) The current implementation considers only viewport-dependent media features."
             },
             {
                 "name": "styleSheetChanged",
                 "parameters": [
                     { "name": "styleSheetId", "$ref": "StyleSheetId" }
                 ],
                 "description": "Fired whenever a stylesheet is changed as a result of the client operation."
             },
             {
                 "name": "styleSheetAdded",
                 "parameters": [
                     { "name": "header", "$ref": "CSSStyleSheetHeader", "description": "Added stylesheet metainfo." }
                 ],
                 "description": "Fired whenever an active document stylesheet is added."
             },
             {
                 "name": "styleSheetRemoved",
                 "parameters": [
                     { "name": "styleSheetId", "$ref": "StyleSheetId", "description": "Identifier of the removed stylesheet." }
                 ],
                 "description": "Fired whenever an active document stylesheet is removed."
-            },
-            {
-                "name": "namedFlowCreated",
-                "parameters": [
-                    { "name": "namedFlow", "$ref": "NamedFlow", "description": "The new Named Flow." }
-                ],
-                "description": "Fires when a Named Flow is created.",
-                "hidden": true
-            },
-            {
-                "name": "namedFlowRemoved",
-                "parameters": [
-                    { "name": "documentNodeId", "$ref": "DOM.NodeId", "description": "The document node id." },
-                    { "name": "flowName", "type": "string", "description": "Identifier of the removed Named Flow." }
-                ],
-                "description": "Fires when a Named Flow is removed: has no associated content nodes and regions.",
-                "hidden": true
-            },
-            {
-                "name": "regionLayoutUpdated",
-                "parameters": [
-                    { "name": "namedFlow", "$ref": "NamedFlow", "description": "The Named Flow whose layout may have changed." }
-                ],
-                "description": "Fires when a Named Flow's layout may have changed.",
-                "hidden": true
-            },
-            {
-                "name": "regionOversetChanged",
-                "parameters": [
-                    { "name": "namedFlow", "$ref": "NamedFlow", "description": "The Named Flow containing the regions whose regionOverset values changed." }
-                ],
-                "description": "Fires if any of the regionOverset values changed in a Named Flow's region chain.",
-                "hidden": true
             }
         ]
     },
     {
         "domain": "Timeline",
         "description": "Timeline provides its clients with instrumentation records that are generated during the page runtime. Timeline instrumentation can be started and stopped using corresponding commands. While timeline is started, it is generating timeline event records.",
         "types": [
             {
                 "id": "Counters",
                 "type": "object",
@@ skipping 1277 matching lines @@
                 ],
                 "handlers": ["browser", "frontend"]
             },
             {
                 "name": "tracingComplete",
                 "handlers": ["browser", "frontend"]
             }
         ]
     }]
 }