doc: remove inline styles

Change-Id: I7ca7e9a2d4cf97cf33c60a9a4d0ba5fb0ca6e44c
Reviewed-on: https://go-review.googlesource.com/35098Reviewed-by: Chris Broadfoot <cbro@golang.org>

doc/install.html

@@ -250,7 +250,7 @@ $ <b>cd $HOME/go/src/hello</b>
 $ <b>go build</b>
 </pre>
 
-<pre class="testWindows" style="display: none">
+<pre class="testWindows">
 C:\&gt; <b>cd %USERPROFILE%\go\src\hello</b>
 C:\Users\Gopher\go\src\hello&gt; <b>go build</b>
 </pre>
@@ -267,7 +267,7 @@ $ <b>./hello</b>
 hello, world
 </pre>
 
-<pre class="testWindows" style="display: none">
+<pre class="testWindows">
 C:\Users\Gopher\go\src\hello&gt; <b>hello</b>
 hello, world
 </pre>