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`.

1 files changed, 15 insertions, 5 deletions

diff --git a/test/reference-types.wast.fromBinary b/test/reference-types.wast.fromBinary
index 534dceff5..82ade2c15 100644
--- a/test/reference-types.wast.fromBinary
+++ b/test/reference-types.wast.fromBinary
@@ -309,7 +309,9 @@
   )
   (drop
    (try (result anyref)
-    (local.get $1)
+    (do
+     (local.get $1)
+    )
     (catch
      (exnref.pop)
     )
@@ -317,7 +319,9 @@
   )
   (drop
    (try (result anyref)
-    (ref.func $foo)
+    (do
+     (ref.func $foo)
+    )
     (catch
      (drop
       (exnref.pop)
@@ -328,7 +332,9 @@
   )
   (drop
    (try (result funcref)
-    (ref.func $foo)
+    (do
+     (ref.func $foo)
+    )
     (catch
      (drop
       (exnref.pop)
@@ -339,7 +345,9 @@
   )
   (drop
    (try (result exnref)
-    (ref.null)
+    (do
+     (ref.null)
+    )
     (catch
      (exnref.pop)
     )
@@ -347,7 +355,9 @@
   )
   (drop
    (try (result nullref)
-    (ref.null)
+    (do
+     (ref.null)
+    )
     (catch
      (drop
       (exnref.pop)