[AGGS] Pass current docid being processed to scripts.

Scripts may internally cache based on docid (as expressions do). This
change makes numeric aggregations using scripts pass the docid when
it changes.

src/main/java/org/elasticsearch/search/aggregations/support/ValuesSource.java

@@ -465,6 +465,7 @@ public abstract class ValuesSource {
 
                 @Override
                 public int setDocument(int docId) {
+                    script.setNextDocId(docId);
                     return source.longValues().setDocument(docId);
                 }
 
@@ -488,6 +489,7 @@ public abstract class ValuesSource {
 
                 @Override
                 public int setDocument(int docId) {
+                    script.setNextDocId(docId);
                     return source.doubleValues().setDocument(docId);
                 }