Merge pull request #1842 from NathanWalker/es6-shim-definitions

fix(es6): objectcontstructor assign

es6.d.ts

@@ -1 +1,9 @@
-declare var Symbol: any;
+declare var Symbol: any;
+
+interface ObjectConstructor {
+    assign(target: any, ...sources: any[]): any;
+    is(value1: any, value2: any): boolean;
+    setPrototypeOf(o: any, proto: any): any;
+}
+
+declare var Object: ObjectConstructor;