Require `then` and `else` with `if` (#6201)

We previously supported (and primarily used) a non-standard text format for
conditionals in which the condition, if-true expression, and if-false expression
were all simply s-expression children of the `if` expression. The standard text
format, however, requires the use of `then` and `else` forms to introduce the
if-true and if-false arms of the conditional. Update the legacy text parser to
require the standard format and update all tests to match. Update the printer to
print the standard format as well.

The .wast and .wat test inputs were mechanically updated with this script:
https://gist.github.com/tlively/85ae7f01f92f772241ec994c840ccbb1

1 files changed, 72 insertions, 24 deletions

diff --git a/test/wasm2js/emscripten.wast b/test/wasm2js/emscripten.wast
index 823297476..453c9d312 100644
--- a/test/wasm2js/emscripten.wast
+++ b/test/wasm2js/emscripten.wast
@@ -75,58 +75,94 @@
    (i32.add (i32.const 9) (i32.const 10))
   )
   (if (i32.eq (i32.load (i32.const 100)) (i32.const 1))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_s (i32.load (i32.const 104)) (i32.const 2))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_u (i32.load (i32.const 108)) (i32.const 3))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.eq (i32.load16_s (i32.const 112)) (i32.const 1))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_s (i32.load16_s (i32.const 116)) (i32.const 2))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_s (i32.load16_u (i32.const 120)) (i32.const 2))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_u (i32.load16_s (i32.const 124)) (i32.const 3))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_u (i32.load16_u (i32.const 128)) (i32.const 3))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_s (i32.load8_s (i32.const 132)) (i32.const 2))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_s (i32.load8_u (i32.const 136)) (i32.const 2))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_u (i32.load8_s (i32.const 140)) (i32.const 3))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.lt_u (i32.load8_u (i32.const 144)) (i32.const 3))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.shr_u (call $bools (i32.const 314159)) (i32.const 7))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.shr_s (call $bools (i32.const 314159)) (i32.const 8))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.trunc_f32_u (call $getf32))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.trunc_f32_s (call $getf32))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.trunc_f64_u (call $getf64))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if (i32.trunc_f64_s (call $getf64))
-   (call  $bar)
+   (then
+    (call  $bar)
+   )
   )
   (if
     (i32.add
@@ -136,7 +172,9 @@
       )
       (call $geti32)
     )
-    (call $bar)
+    (then
+      (call $bar)
+    )
   )
   (if
     (i32.add
@@ -146,7 +184,9 @@
         (call $geti32)
       )
     )
-    (call $bar)
+    (then
+      (call $bar)
+    )
   )
   (if
     (i32.add
@@ -159,7 +199,9 @@
         (call $geti32)
       )
     )
-    (call $bar)
+    (then
+      (call $bar)
+    )
   )
   (if
     (i32.add
@@ -184,7 +226,9 @@
         )
       )
     )
-    (call $bar)
+    (then
+      (call $bar)
+    )
   )
  )
  (func $geti32 (result i32)
@@ -230,11 +274,15 @@
   (drop (call $bools (i32.xor (local.get $x) (i32.const 1))))
   (if
     (i32.xor (local.get $x) (i32.const 1))
-    (drop (call $bools (i32.const 2)))
+    (then
+      (drop (call $bools (i32.const 2)))
+    )
   )
   (if
     (i32.xor (local.get $x) (i32.const 2))
-    (drop (call $bools (i32.const 2)))
+    (then
+      (drop (call $bools (i32.const 2)))
+    )
   )
   (drop (call $bools (i32.eqz (i32.xor (local.get $x) (i32.const 1)))))
   (unreachable)