Add failing test For extra whitespace in nested partials.

test/fixtures/examples/nested_partials/nested_partials.txt

@@ -3,5 +3,8 @@
     <third>
       FOURTH!
     </third>
+    <third>
+      FOURTH!FOURTH!
+    </third>
   </second>
 </first>

test/fixtures/examples/nested_partials/partials/fourth_inline.mustache

@@ -0,0 +1 @@
+{{ val }}

test/fixtures/examples/nested_partials/partials/third.mustache

@@ -1,3 +1,6 @@
 <third>
   {{> fourth }}
 </third>
+<third>
+  {{> fourth_inline }}{{> fourth_inline }}
+</third>