DevTools: enable object previews experiment by default

third_party/WebKit/LayoutTests/inspector/console/console-dir-expected.txt

 CONSOLE MESSAGE: line 9: test1,test2
 CONSOLE MESSAGE: line 10: [object NodeList]
 CONSOLE MESSAGE: line 11: [object XPathResult]
 CONSOLE MESSAGE: line 21: [object Object]
 CONSOLE MESSAGE: line 24: function () {}
 CONSOLE MESSAGE: line 28: [object Object]
 CONSOLE MESSAGE: line 31: [object Object]
 CONSOLE MESSAGE: line 32: [object Object]
 CONSOLE MESSAGE: line 34: function get __proto__() { [native code] }
 CONSOLE MESSAGE: line 39: [object Uint8Array]
@@ skipping 20 matching lines @@
     $foo5_: 0
     "a↵↵b↵c": "a↵↵b↵c"
     c d: "c d"
     negZero: -0
     __proto__: Object
 console-dir.html:19 ƒ anonymous()
     arguments: null
     caller: null
     length: 0
     name: ""
-    prototype: Object
+    prototype: {constructor: ƒ}
     __proto__: ƒ ()
     [[FunctionLocation]]: console-dir.html:19
     [[Scopes]]: Scopes[1]
 console-dir.html:23 inner
     __proto__: Object
 console-dir.html:26 Object
     No Properties
 console-dir.html:27 Object
-    foo: Object
+    foo: 
         No Properties
     __proto__: Object
 console-dir.html:29 ƒ __proto__()
     arguments: null
     caller: null
     length: 0
     name: "get __proto__"
     __proto__: ƒ ()
 console-dir.html:34 Uint8Array(400000000)
     [0 … 99999999]
     [100000000 … 199999999]
     [200000000 … 299999999]
     [300000000 … 399999999]
     __proto__: TypedArray
 console-dir.html:39 Event
     bubbles: false
     cancelBubble: false
     cancelable: false
     composed: false
     currentTarget: null
     defaultPrevented: false
     eventPhase: 0
     isTrusted: false
-    path: Array(0)
+    path: []
     returnValue: true
     srcElement: null
     target: null
     type: ""
     timeStamp: 0
     __proto__: Event