feat(change_detection): allow all legal programs in the dev mode

BEFORE:

The following would throw in the dev mode because `f` would return a new array when called by checkNoChanges.

@Component({
  template: `
    {{f()}}
  `
})
class A {
  f() { return [1]; }
}

AFTER:

The checkNoChanges function compares only primitives types for equality, and deeply compares iterables. Other objects cannot cause checkNoChanges to throw. This means that the dev mode would never fail given a legal program, but may allow some illegal programs.

modules/angular2/test/core/change_detection/change_detector_spec.ts

@@ -887,6 +887,13 @@ export function main() {
                   'Expression [\'"]a in location[\'"] has changed after it was checked'));
         });
 
+        it('should not throw when two arrays are structurally the same', () => {
+          var val = _createChangeDetector('a', new TestDataWithGetter(() => ['value']));
+          val.changeDetector.detectChanges();
+
+          expect(() => { val.changeDetector.checkNoChanges(); }).not.toThrow();
+        });
+
         it('should not break the next run', () => {
           var val = _createChangeDetector('a', new TestData('value'));
           expect(() => val.changeDetector.checkNoChanges())
@@ -1597,6 +1604,12 @@ class TestData {
   constructor(public a: any) {}
 }
 
+class TestDataWithGetter {
+  constructor(private fn: Function) {}
+
+  get a() { return this.fn(); }
+}
+
 class TestDispatcher implements ChangeDispatcher {
   log: string[];
   debugLog: string[];

modules/angular2/test/core/change_detection/change_detector_util_spec.ts

@@ -0,0 +1,60 @@
+import {
+  ddescribe,
+  describe,
+  it,
+  iit,
+  xit,
+  expect,
+  beforeEach,
+  afterEach
+} from 'angular2/testing_internal';
+
+import {ChangeDetectionUtil} from 'angular2/src/core/change_detection/change_detection_util';
+
+export function main() {
+  describe("ChangeDetectionUtil", () => {
+    describe("devModeEqual", () => {
+      it("should do the deep comparison of iterables", () => {
+        expect(ChangeDetectionUtil.devModeEqual([['one']], [['one']])).toBe(true);
+        expect(ChangeDetectionUtil.devModeEqual(['one'], ['one', 'two'])).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(['one', 'two'], ['one'])).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(['one'], 'one')).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(['one'], new Object())).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual('one', ['one'])).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(new Object(), ['one'])).toBe(false);
+      });
+
+      it("should compare primitive numbers", () => {
+        expect(ChangeDetectionUtil.devModeEqual(1, 1)).toBe(true);
+        expect(ChangeDetectionUtil.devModeEqual(1, 2)).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(new Object(), 2)).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(1, new Object())).toBe(false);
+      });
+
+      it("should compare primitive strings", () => {
+        expect(ChangeDetectionUtil.devModeEqual('one', 'one')).toBe(true);
+        expect(ChangeDetectionUtil.devModeEqual('one', 'two')).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(new Object(), 'one')).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual('one', new Object())).toBe(false);
+      });
+
+      it("should compare primitive booleans", () => {
+        expect(ChangeDetectionUtil.devModeEqual(true, true)).toBe(true);
+        expect(ChangeDetectionUtil.devModeEqual(true, false)).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(new Object(), true)).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(true, new Object())).toBe(false);
+      });
+
+      it("should compare null", () => {
+        expect(ChangeDetectionUtil.devModeEqual(null, null)).toBe(true);
+        expect(ChangeDetectionUtil.devModeEqual(null, 1)).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(new Object(), null)).toBe(false);
+        expect(ChangeDetectionUtil.devModeEqual(null, new Object())).toBe(false);
+      });
+
+      it("should return true for other objects", () => {
+        expect(ChangeDetectionUtil.devModeEqual(new Object(), new Object())).toBe(true);
+      });
+    });
+  });
+}