feat(md-navbar): add auto-height style

src/navbar/navbar.css

@@ -1,3 +1,7 @@
 md-navbar .primary {
   transition: all .3s ease-out;
 }
+
+md-navbar .primary.md-auto-height {
+  height: auto;
+}

src/navbar/navbar.html

@@ -1,7 +1,7 @@
 <template>
   <require from="./navbar.css"></require>
   <div ref="fixedAnchor">
-    <nav class="primary">
+    <nav class="primary" ref="nav">
       <div class="nav-wrapper">
         <slot></slot>
       </div>

src/navbar/navbar.js

@@ -10,6 +10,9 @@ export class MdNavbar {
   @bindable({
     defaultBindingMode: bindingMode.oneTime
   }) mdFixed;
+  @bindable({
+    defaultBindingMode: bindingMode.oneTime
+  }) mdAutoHeight;
   fixedAttributeManager;
 
   constructor(element) {
@@ -18,14 +21,21 @@ export class MdNavbar {
 
   attached() {
     this.fixedAttributeManager = new AttributeManager(this.fixedAnchor);
+    this.navAttributeManager = new AttributeManager(this.nav);
     if (getBooleanFromAttributeValue(this.mdFixed)) {
       this.fixedAttributeManager.addClasses('navbar-fixed');
     }
+    if (getBooleanFromAttributeValue(this.mdAutoHeight)) {
+      this.navAttributeManager.addClasses('md-auto-height');
+    }
   }
 
   detached() {
     if (getBooleanFromAttributeValue(this.mdFixed)) {
       this.fixedAttributeManager.removeClasses('navbar-fixed');
     }
+    if (getBooleanFromAttributeValue(this.mdAutoHeight)) {
+      this.navAttributeManager.addClasses('md-auto-height');
+    }
   }
 }