feat(bootstraping): application bootstrapping implementation.

Entry-point to bootstrapping is a rootComponent. The bootstrapping
method, uses the component's selector to find the insertion element in
the DOM, and attaches the component in its ShadowRoot.

modules/facade/src/dom.dart

@@ -17,6 +17,9 @@ class DOM {
   static query(selector) {
     return document.querySelector(selector);
   }
+  static Element querySelector(el, String selector) {
+    return el.querySelector(selector);
+  }
   static ElementList querySelectorAll(el, String selector) {
     return el.querySelectorAll(selector);
   }
@@ -52,6 +55,10 @@ class DOM {
     t.setInnerHtml(html, treeSanitizer:identitySanitizer);
     return t;
   }
+  static createElement(tagName, [doc=null]) {
+    if (doc == null) doc = document;
+    return doc.createElement(tagName);
+  }
   static clone(Node node) {
     return node.clone(true);
   }
@@ -82,4 +89,10 @@ class DOM {
   static Node templateAwareRoot(Element el) {
     return el is TemplateElement ? el.content : el;
   }
+  static HtmlDocument createHtmlDocument() {
+    return document.implementation.createHtmlDocument('fakeTitle');
+  }
+  static HtmlDocument defaultDoc() {
+    return document;
+  }
 }

modules/facade/src/dom.es6

@@ -13,6 +13,9 @@ export class DOM {
   static query(selector) {
     return document.querySelector(selector);
   }
+  static querySelector(el, selector:string):Node {
+    return el.querySelector(selector);
+  }
   static querySelectorAll(el, selector:string):NodeList {
     return el.querySelectorAll(selector);
   }
@@ -48,6 +51,9 @@ export class DOM {
     t.innerHTML = html;
     return t;
   }
+  static createElement(tagName, doc=document) {
+    return doc.createElement(tagName);
+  }
   static clone(node:Node) {
     return node.cloneNode(true);
   }
@@ -84,4 +90,10 @@ export class DOM {
   static templateAwareRoot(el:Element):Node {
     return el instanceof TemplateElement ? el.content : el;
   }
+  static createHtmlDocument() {
+    return document.implementation.createHTMLDocument();
+  }
+  static defaultDoc() {
+    return document;
+  }
 }