graying corpus statistic(plus tests+vc test fixed) and fix vc serialization

Change-Id: I3f934c2cc0ebbb0a91b5fa8f529bf3f5c3ebd391
(cherry picked from commit 172d6a4bbc7d29a0fe7c23b114fbbf485e2f4aeb)
diff --git a/dev/js/src/vc/doc.js b/dev/js/src/vc/doc.js
index 996c347..2a0e872 100644
--- a/dev/js/src/vc/doc.js
+++ b/dev/js/src/vc/doc.js
@@ -149,6 +149,10 @@
         e.appendChild(op.element());
       };
       
+      if(KorAP.vc){
+        KorAP.vc.checkGrayingStat();
+      }
+      
       return e;
     },
 
@@ -616,9 +620,12 @@
       };
     },
 
+    incomplete : function () {
+      return !(this.matchop() && this.key() && this.value());
+    },
 
     toQuery : function () {
-      if (!this.matchop() || !this.key())
+      if (this.incomplete())
         return "";
 
       // Build doc string based on key