Fix crash generating facades for loasd. Fix bug in how we handle TypePredicates. Add test for TypeP…

test/function_test.ts

 /// <reference path="../typings/mocha/mocha.d.ts"/>
 import {expectTranslate} from './test_support';
 
 describe('functions', () => {
   it('supports declarations', () => {
     expectTranslate('function x() {}').to.equal(`@JS()
 external x();`);
   });
   it('hide param default values', () => {
     expectTranslate('function x(a = 42, b = 1) { return 42; }').to.equal(`@JS()
 external x([a, b]);`);
     expectTranslate('function x(p1, a = 42, b = 1, p2) { return 42; }').to.equal(`@JS()
 external x(p1, [a, b, p2]);`);
   });
   it('translates optional parameters', () => {
     expectTranslate('function x(a?: number, b?: number) { return 42; }').to.equal(`@JS()
 external x([num a, num b]);`);
     expectTranslate('function x(p1, a?: number, b?: number, p2) { return 42; }').to.equal(`@JS()
 external x(p1, [num a, num b, p2]);`);
   });
   it('supports empty returns', () => {
     expectTranslate('function x() { return; }').to.equal(`@JS()
 external x();`);
   });
 
+  it('supports type predicates', () => {
+    expectTranslate('function isArrayBuffer(value?: any): value is ArrayBuffer;')
+        .to.equal(`import "dart:typed_data" show ByteBuffer;
+
+@JS()
+external bool /*value is ByteBuffer*/ isArrayBuffer([dynamic value]);`);
+  });
+
   it('polyfill var args', () => {
     expectTranslate('function x(...a: number[]) { return 42; }').to.equal(`@JS()
 external x([num a1, num a2, num a3, num a4, num a5]);`);
   });
   it('supports function parameters', () => {
     expectTranslate('function f(fn: (a: A, b: B) => C) {}').to.equal(`@JS()
 external f(C fn(A a, B b));`);
   });
   it('supports recursive function parameters', () => {
     expectTranslate('function f(fn: (a: (b: B) => C) => D) {}').to.equal(`@JS()
@@ skipping 57 matching lines @@
   });
   it('replaces type usage sites, but not idents', () => {
     expectTranslate(`function wobble<T, U>(u: U): T { }`).to.equal(`@JS()
 external dynamic/*=T*/ wobble/*<T, U>*/(dynamic/*=U*/ u);`);
   });
   it('translates generic calls', () => {
     expectTranslate(`function wobble<T>(foo: T): T { }`).to.equal(`@JS()
 external dynamic/*=T*/ wobble/*<T>*/(dynamic/*=T*/ foo);`);
   });
 });