[reference-types] Support passive elem segments (#3572)

Passive element segments do not belong to any table, so the link between
Table and elem needs to be weaker; i.e. an elem may have a table in case
of active segments, or simply be a collection of function references in
case of passive/declarative segments.

This PR takes Table::Segment out and turns it into a first class module
element just like tables and functions. It also implements early support
for parsing, printing, encoding and decoding passive/declarative elem
segments.

1 files changed, 9 insertions, 2 deletions

diff --git a/test/multi-table.wast.fromBinary b/test/multi-table.wast.fromBinary
index 1bfd568da..13604e69d 100644
--- a/test/multi-table.wast.fromBinary
+++ b/test/multi-table.wast.fromBinary
@@ -4,12 +4,19 @@
  (elem (table $t1) (i32.const 0) func $f)
  (table $t2 3 3 funcref)
  (elem (table $t2) (i32.const 0) func $f)
- (elem (table $t2) (i32.const 1) func $f $g)
+ (elem $activeNonZeroOffset (table $t2) (i32.const 1) func $f $g)
+ (elem $passive func $f $g)
+ (elem declare func $h)
  (func $f
-  (nop)
+  (drop
+   (ref.func $h)
+  )
  )
  (func $g
   (nop)
  )
+ (func $h
+  (nop)
+ )
 )