Builtins rewrite with type parameter inference; Small integer math optimizations; Switchify

tests/compiler/assert.optimized.wast

@@ -4,6 +4,18 @@
  (export "memory" (memory $0))
  (start $start)
  (func $start (; 0 ;) (type $v)
-  (nop)
+  (local $0 i32)
+  (if
+   (i32.eqz
+    (if (result i32)
+     (tee_local $0
+      (i32.const 1)
+     )
+     (get_local $0)
+     (unreachable)
+    )
+   )
+   (unreachable)
+  )
  )
 )