code: private void dble() {
              Assert.check(shared == 0);
              Entry[] oldtable = table;
              Entry[] newtable = new Entry[oldtable.length * 2];
              for (ScopeImpl s = this; s != null; s = s.next) {
                  if (s.table == oldtable) {
                      Assert.check(s == this || s.shared != 0);
                      s.table = newtable;
                      s.hashMask = newtable.length - 1;
                  }
              }
              int n = 0;
              for (int i = oldtable.length; --i >= 0; ) {
                  Entry e = oldtable[i];
                  if (e != null && e != sentinel) {
                      table[getIndex(e.sym.name)] = e;
                      n++;
                  }
              }
              // We don't need to update nelems for shared inherited scopes,
              // since that gets handled by leave().
              nelems = n;
          }
docs: Double size of hash table.