ES6 symbols: Implement Symbol intrinsic and basic functionality

src/symbol.js

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-// Flags: --allow-natives-syntax
+"use strict";
 
-function foo(k, p) {
-  for (var i = 0; i < 1; i++) {
-    p = Math.min(p, i);
-  }
-  m = Math.floor((k | 0) / p);
+var $Symbol = function() { return %CreateSymbol() }
+global.Symbol = $Symbol
+
+// Symbols only have a toString method and no prototype.
+var SymbolDelegate = {
+  __proto__: null,
+  toString: $Object.prototype.toString
 }
 
-foo(0, 1);
-foo(0, 1);
-%OptimizeFunctionOnNextCall(foo);
-foo(0, 1);
+$Object.freeze(SymbolDelegate)