Split WebIDL into two parts.

Workaround for w3c/respec#1717

Author: mgiuca

index.html

@@ -196,7 +196,8 @@ <h2>
   DOMString method = "GET";
   required ShareTargetParams params;
 };
-
+</pre>
+      <pre class="idl">
 partial dictionary WebAppManifest {
   ShareTarget share_target;
 };