use typeof to check for presence of JSON global

weswigham · weswigham · commit a5a6c10322ed · 2015-12-02T21:06:32.000-08:00
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
@@ -2400,7 +2400,7 @@ namespace ts {
      * Serialize an object graph into a JSON string. This is intended only for use on an acyclic graph
      * as the fallback implementation does not check for circular references by default.
      */
-    export const stringify: (value: any) => string = JSON && JSON.stringify
+    export const stringify: (value: any) => string = typeof JSON !== "undefined" && JSON.stringify
         ? JSON.stringify
         : stringifyFallback;
 
