refactor(jqLite): remove jqLite show/hide support

it turns out that even with our tricks, jqLite#show is not usable in
practice and definitely not on par with jQuery. so rather than
introducing half-baked apis which introduce issues, I'm removing them.

I also removed show/hide uses from docs, since they are not needed.

Breaks jqLite.hide/jqLite.show which are no longer available.

docs/src/templates/doc_widgets.css

@@ -1,9 +1,3 @@
-@namespace doc url("http://docs.angularjs.org/");
-
-doc\:example {
-  display: none;
-}
-
 ul.doc-example {
   list-style-type: none;
   position: relative;

docs/src/templates/doc_widgets.js

@@ -23,7 +23,6 @@
 
   angular.widget('doc:example', function(element){
     this.descend(true); //compile the example code
-    element.hide();
 
     //jQuery find() methods in this widget contain primitive selectors on purpose so that we can use
     //jqlite instead. jqlite's find() method currently supports onlt getElementsByTagName!
@@ -53,7 +52,6 @@
 
     element.html('');
     element.append(tabs);
-    element.show();
 
     var script = (exampleSrc.match(/<script[^\>]*>([\s\S]*)<\/script>/) || [])[1] || '';
     try {