feat(Binding): improve errors

fix #4358

Closes #4360

modules/angular2/test/core/di/binding_spec.ts

@@ -0,0 +1,31 @@
+import {
+  AsyncTestCompleter,
+  beforeEach,
+  ddescribe,
+  describe,
+  expect,
+  iit,
+  inject,
+  it,
+  xit,
+} from 'angular2/test_lib';
+
+import {bind} from 'angular2/core';
+
+export function main() {
+  describe('binding', () => {
+
+    describe('type errors', () => {
+
+      it('should throw when trying to create a class binding and not passing a class', () => {
+        expect(() => { bind('foo').toClass(<any>0); })
+            .toThrowError('Trying to create a class binding but "0" is not a class!');
+      });
+
+      it('should throw when trying to create a factory binding and not passing a function', () => {
+        expect(() => { bind('foo').toFactory(<any>0); })
+            .toThrowError('Trying to create a factory binding but "0" is not a function!');
+      });
+    });
+  });
+}