Fix success or failed determine code bug

currently implementation was erroneous decision, e.g. _infrastructure/tests/typescript/tsc.js not exists.

_infrastructure/tests/runner.js

@@ -691,7 +691,7 @@ var DefinitelyTyped;
             }
             Object.defineProperty(TestResult.prototype, "success", {
                 get: function () {
-                    return this.exitCode !== 1;
+                    return this.exitCode === 0;
                 },
                 enumerable: true,
                 configurable: true

_infrastructure/tests/runner.ts

@@ -139,7 +139,7 @@ module DefinitelyTyped.TestManager {
         exitCode:number;
 
         public get success():boolean {
-            return this.exitCode !== 1;
+            return this.exitCode === 0;
         }
     }