DevTools: Show preview in console of ES6 Map, Set, WeakMap and WeakSet entries.

LayoutTests/inspector/console/console-dir-es6-expected.txt

 CONSOLE MESSAGE: line 15: [object Object]
 CONSOLE MESSAGE: line 18: Symbol()
 CONSOLE MESSAGE: line 22: [object Map]
 CONSOLE MESSAGE: line 22: [object WeakMap]
 CONSOLE MESSAGE: line 26: [object Set]
 CONSOLE MESSAGE: line 26: [object WeakSet]
+CONSOLE MESSAGE: line 34: [object Set]
 Tests that console logging dumps proper messages.
 
 console-dir-es6.html:15 Object
     a: 1
     Symbol(): 2
     Symbol(Symbol.iterator): Symbol(foo)
     Symbol(a): 3
     Symbol(a): Symbol(Symbol.iterator)
     __proto__: Object
 console-dir-es6.html:18 Symbol()
 console-dir-es6.html:22 Map
     size: (...)
     __proto__: Map
     <entries>[1]
     0: {key:Object, value:Object}
 console-dir-es6.html:22 WeakMap
     __proto__: WeakMap
     <entries>[1]
     0: {key:Object, value:Object}
 console-dir-es6.html:26 Set
     size: (...)
     __proto__: Set
     <entries>[1]
     0: Object
 console-dir-es6.html:26 WeakSet
     __proto__: WeakSet
     <entries>[1]
     0: Object
+console-dir-es6.html:34 Set
+    size: (...)
+    __proto__: Set
+    <entries>[1]
+    0: Set