Change from storing Signature to HeapType on CallIndirect (#4352)

With nominal function types, this change makes it so that we preserve the
identity of the function type used with call_indirect instructions rather than
recreating a function heap type, which may or may not be the same as the
originally parsed heap type, from the function signature during module writing.

This will simplify the type system implementation by removing the need to store
a "canonical" nominal heap type for each unique signature. We previously
depended on those canonical types to avoid creating multiple duplicate function
types during module writing, but now we aren't creating any new function types
at all.

1 files changed, 1 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 140a8e1b5..4a1bcb9ce 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,7 @@ Current Trunk
   const binaryen = await Binaryen();
   ...
   ```
+- CallIndirect changed from storing a Signature to storing a HeapType
 
 v102
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