feat(dom): add getBaseHref method

modules/angular2/src/dom/browser_adapter.dart

@@ -318,4 +318,9 @@ class BrowserDomAdapter extends GenericBrowserDomAdapter {
   getLocation() {
     return window.location;
   }
+  getBaseHref() {
+    var uri = document.baseUri;
+    var baseUri = Uri.parse(uri);
+    return baseUri.path;
+  }
 }

modules/angular2/src/dom/browser_adapter.es6

@@ -381,4 +381,17 @@ export class BrowserDomAdapter extends GenericBrowserDomAdapter {
   getLocation() {
     return window.location;
   }
+  getBaseHref() {
+    return relativePath(document.baseURI);
+  }
+}
+
+// based on urlUtils.js in AngularJS 1
+var urlParsingNode = null;
+function relativePath(url) {
+  if (isBlank(urlParsingNode)) {
+    urlParsingNode = document.createElement("a");
+  }
+  urlParsingNode.setAttribute('href', url);
+  return (urlParsingNode.pathname.charAt(0) === '/') ? urlParsingNode.pathname : '/' + urlParsingNode.pathname;
 }

modules/angular2/src/dom/dom_adapter.js

@@ -292,4 +292,7 @@ export class DomAdapter {
   getLocation() {
     throw _abstract();
   }
+  getBaseHref() {
+    throw _abstract();
+  }
 }

modules/angular2/src/dom/html_adapter.dart

@@ -297,4 +297,7 @@ class Html5LibDomAdapter implements DomAdapter {
   getLocation() {
     throw 'not implemented';
   }
+  getBaseHref() {
+    throw 'not implemented';
+  }
 }