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, 1 insertions, 1 deletions

diff --git a/test/try-body-multiple-insts.wasm.fromBinary b/test/try-body-multiple-insts.wasm.fromBinary
index ba243fdfc..1ecbdbbc6 100644
--- a/test/try-body-multiple-insts.wasm.fromBinary
+++ b/test/try-body-multiple-insts.wasm.fromBinary
@@ -9,7 +9,7 @@
  (func $2
   (local $0 exnref)
   (try
-   (block
+   (do
     (call $0)
     (call $1)
    )