feat(Ruler): introduce Ruler service

Closes #1089

Closes #1253

modules/angular2/test/services/ruler_spec.js

@@ -0,0 +1,57 @@
+import {AsyncTestCompleter, inject, ddescribe, describe, it, iit, xit, expect, SpyObject} from 'angular2/test_lib';
+
+import {DOM, DomAdapter} from 'angular2/src/dom/dom_adapter';
+import {NgElement} from 'angular2/src/core/dom/element';
+
+import {Ruler, Rectangle} from 'angular2/src/services/ruler';
+import {createRectangle} from './rectangle_mock';
+
+class DomAdapterMock extends DomAdapter {
+  rect;
+  constructor(rect) {
+    super();
+    this.rect = rect;
+  }
+
+  getBoundingClientRect(elm) {
+    return this.rect;
+  }
+}
+
+function assertDimensions(rect: Rectangle, left, right, top, bottom, width, height) {
+  expect(rect.left).toEqual(left);
+  expect(rect.right).toEqual(right);
+  expect(rect.top).toEqual(top);
+  expect(rect.bottom).toEqual(bottom);
+  expect(rect.width).toEqual(width);
+  expect(rect.height).toEqual(height);
+}
+
+export function main() {
+
+  describe('ruler service', () => {
+
+    it('should allow measuring NgElements',
+      inject([AsyncTestCompleter], (async) => {
+        var ruler = new Ruler(new DomAdapterMock(createRectangle(10, 20, 200, 100)));
+
+        ruler.measure(new NgElement(null)).then((rect) => {
+          assertDimensions(rect, 10, 210, 20, 120, 200, 100);
+          async.done();
+        });
+      }));
+
+
+    it('should return 0 for all rectangle values while measuring elements in a document fragment',
+      inject([AsyncTestCompleter], (async) => {
+        var ruler = new Ruler(DOM);
+
+        ruler.measure(new NgElement(DOM.createElement('div'))).then((rect) => {
+          //here we are using an element created in a doc fragment so all the measures will come back as 0
+          assertDimensions(rect, 0, 0, 0, 0, 0, 0);
+          async.done();
+        });
+    }));
+
+  });
+}