Use ts.indexOf instead of Array.prototype.indexOf

(keep consistent with the rest of codebase, and thus enable ES3-compatibility of tsc and services)

src/compiler/checker.ts

@@ -3731,7 +3731,7 @@ namespace ts {
             if (node.initializer) {
                 const signatureDeclaration = <SignatureDeclaration>node.parent;
                 const signature = getSignatureFromDeclaration(signatureDeclaration);
-                const parameterIndex = signatureDeclaration.parameters.indexOf(node);
+                const parameterIndex = ts.indexOf(signatureDeclaration.parameters, node);
                 Debug.assert(parameterIndex >= 0);
                 return parameterIndex >= signature.minArgumentCount;
             }