feat(core): provide support for relative assets for components

Assets defined for `templateUrl` and `styleUrls` can now be loaded
in relative to where the component file is placed so long as the
`moduleId` is set within the component annotation.

Closes #5634

modules/playground/e2e_test/relative_assets/assets_spec.dart

@@ -0,0 +1,3 @@
+library playground.e2e_test.relative_assets.assets_spec;
+
+main() {}

modules/playground/e2e_test/relative_assets/assets_spec.ts

@@ -0,0 +1,34 @@
+import {verifyNoBrowserErrors} from 'angular2/src/testing/e2e_util';
+import {Promise} from 'angular2/src/facade/async';
+
+function waitForElement(selector) {
+  var EC = (<any>protractor).ExpectedConditions;
+  // Waits for the element with id 'abc' to be present on the dom.
+  browser.wait(EC.presenceOf($(selector)), 20000);
+}
+
+describe('relative assets relative-app', () => {
+
+  afterEach(verifyNoBrowserErrors);
+
+  var URL = 'playground/src/relative_assets/';
+
+  it('should load in the templateUrl relative to the my-cmp component', () => {
+    browser.get(URL);
+
+    waitForElement('my-cmp .inner-container');
+    expect(element.all(by.css('my-cmp .inner-container')).count()).toEqual(1);
+  });
+
+  it('should load in the styleUrls relative to the my-cmp component', () => {
+    browser.get(URL);
+
+    waitForElement('my-cmp .inner-container');
+    var elem = element(by.css('my-cmp .inner-container'));
+    var width = browser.executeScript(function(e) {
+      return parseInt(window.getComputedStyle(e).width);
+    }, elem.getWebElement());
+
+    expect(width).toBe(432);
+  });
+});