In ts.performance.now, bind window.performance.now

Using an arrow function. Previously, it was set directly to
window.performance.now, which fails when used on Chrome.

Author: sandersn

src/compiler/performance.ts

@@ -2,7 +2,7 @@
 namespace ts {
     declare const performance: { now?(): number } | undefined;
     /** Gets a timestamp with (at least) ms resolution */
-    export const timestamp = typeof performance !== "undefined" && performance.now ? performance.now : Date.now ? Date.now : () => +(new Date());
+    export const timestamp = typeof performance !== "undefined" && performance.now ? () => performance.now() : Date.now ? Date.now : () => +(new Date());
 }
 
 /*@internal*/
@@ -106,4 +106,4 @@ namespace ts.performance {
         measures = undefined;
         profilerEvent = undefined;
     }
-}
+}