Typed continuations: cont.new instructions (#6308)

This PR is part of a series that adds basic support for the [typed
continuations/wasmfx proposal](https://github.com/wasmfx/specfx).

This particular PR adds support for the `cont.new` instruction for creating
continuations, documented [here(https://github.com/wasmfx/specfx/blob/main/proposals/continuations/Overview.md#instructions).

In short, these instructions are of the form `(cont.new $ct)` where `$ct` must
be a continuation type. The instruction takes a single (nullable) function
reference as its argument, which means that the folded representation of the
instruction is of the form `(cont.new $ct (foo ...))`. 

Support for the instruction is implemented in both the old and the new wat
parser.

Note that this PR does not implement validation of the new instruction.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/ir/module-utils.cpp b/src/ir/module-utils.cpp
index 304ddb04d..b61fddd8b 100644
--- a/src/ir/module-utils.cpp
+++ b/src/ir/module-utils.cpp
@@ -341,6 +341,8 @@ struct CodeScanner
       counts.include(get->type);
     } else if (auto* set = curr->dynCast<ArraySet>()) {
       counts.note(set->ref->type);
+    } else if (auto* contNew = curr->dynCast<ContNew>()) {
+      counts.note(contNew->contType);
     } else if (auto* resume = curr->dynCast<Resume>()) {
       counts.note(resume->contType);
     } else if (Properties::isControlFlowStructure(curr)) {