fix: vertically align buttons with the surrounding text.

Also add a section for baseline vertical alignment.

src/components/button/_button-base.scss

@@ -36,7 +36,6 @@ $md-mini-fab-padding: 8px !default;
   // Reset browser <button> styles.
   background: transparent;
   text-align: center;
-  overflow: hidden;
   cursor: pointer;
   user-select: none;
   outline: none;
@@ -46,7 +45,7 @@ $md-mini-fab-padding: 8px !default;
   display: inline-block;
   white-space: nowrap;
   text-decoration: none;
-  vertical-align: middle;
+  vertical-align: baseline;
 
   // Typography.
   font-size: $md-body-font-size-base;

src/demo-app/button/button-demo.html

@@ -1,4 +1,17 @@
 <div class="demo-button">
+  <section>
+    Link
+    <a href="http://www.google.com" md-button color="primary">link</a>
+    Button
+    <button md-button>flat</button>
+  </section>
+  <section>
+    Link
+    <a href="http://www.google.com" md-raised-button color="primary">link</a>
+    Button
+    <button md-raised-button>button</button>
+  </section>
+
   <section>
     <button md-button>flat</button>
     <button md-raised-button>raised</button>