Perform basic HMTL escaping for @example tag code

Review at http://gwt-code-reviews.appspot.com/1026801

Review by: jlabanca@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@9113 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/build-tools/doctool/src/com/google/doctool/custom/ExampleTaglet.java b/build-tools/doctool/src/com/google/doctool/custom/ExampleTaglet.java
index 7d7db70..49c3001 100644
--- a/build-tools/doctool/src/com/google/doctool/custom/ExampleTaglet.java
+++ b/build-tools/doctool/src/com/google/doctool/custom/ExampleTaglet.java
@@ -81,6 +81,9 @@
         });
 
     String slurpSource = Booklet.slurpSource(position);
+    // The <pre> tag still requires '<' and '>' characters to be escaped
+    slurpSource = slurpSource.replace("<", "&lt;");
+    slurpSource = slurpSource.replace(">", "&gt;");
     return "<blockquote><pre>" + slurpSource + "</pre></blockquote>";
   }