Implement ternary using if, see AssemblyScript/assemblyscript#123

tests/compiler/ternary.wast

@@ -0,0 +1,64 @@
+(module
+ (type $v (func))
+ (global $ternary/a (mut i32) (i32.const 0))
+ (memory $0 1)
+ (data (i32.const 4) "\08\00\00\00")
+ (export "memory" (memory $0))
+ (start $start)
+ (func $start (; 0 ;) (type $v)
+  (set_global $ternary/a
+   (if (result i32)
+    (i32.const 0)
+    (unreachable)
+    (i32.const 1)
+   )
+  )
+  (set_global $ternary/a
+   (if (result i32)
+    (i32.const 1)
+    (i32.const 1)
+    (unreachable)
+   )
+  )
+  (set_global $ternary/a
+   (if (result i32)
+    (if (result i32)
+     (i32.const 0)
+     (unreachable)
+     (i32.const 1)
+    )
+    (i32.const 1)
+    (unreachable)
+   )
+  )
+ )
+)
+(;
+[program.elements]
+  clz
+  ctz
+  popcnt
+  rotl
+  rotr
+  abs
+  ceil
+  copysign
+  floor
+  max
+  min
+  nearest
+  sqrt
+  trunc
+  current_memory
+  grow_memory
+  unreachable
+  isNaN
+  isFinite
+  assert
+  sizeof
+  load
+  store
+  ternary/a
+[program.exports]
+  
+;)