Make try body start with 'do' (#2846)

In WebAssembly/exception-handling#52, We decided to put `try` bodies in
a `do` clause to be more consistent with `catch`.

- Before
```wast
(try
  ...
  (catch
    ...
  )
)
```

- After
```wast
(try
  (do
    ...
  )
  (catch
    ...
  )
)
```

Another upside of this change is when there are multiple instructions
within a `try` body, we no longer need to wrap them in a `block`.

2 files changed, 7 insertions, 3 deletions

diff --git a/test/example/c-api-kitchen-sink.c b/test/example/c-api-kitchen-sink.c
index a55862c2c..572e06ace 100644
--- a/test/example/c-api-kitchen-sink.c
+++ b/test/example/c-api-kitchen-sink.c
@@ -305,7 +305,9 @@ void test_core() {
   // Exception handling
 
   // (try
-  //   (throw $a-event (i32.const 0))
+  //   (do
+  //     (throw $a-event (i32.const 0))
+  //   )
   //   (catch
   //     ;; We don't support multi-value yet. Use locals instead.
   //     (local.set 0 (exnref.pop))
diff --git a/test/example/c-api-kitchen-sink.txt b/test/example/c-api-kitchen-sink.txt
index 1b8960a8c..260f51066 100644
--- a/test/example/c-api-kitchen-sink.txt
+++ b/test/example/c-api-kitchen-sink.txt
@@ -1691,8 +1691,10 @@ BinaryenFeatureAll: 1023
        )
       )
       (try
-       (throw $a-event
-        (i32.const 0)
+       (do
+        (throw $a-event
+         (i32.const 0)
+        )
        )
        (catch
         (local.set $5