Replace more .wast references with .wat

tests/binaryen/asmjs.wat

@@ -0,0 +1,18 @@
+(module
+ (type $i (func (param i32) (result i32)))
+ (memory $0 0)
+ (export "test/switch/case/eval" (func $test/switch/case/eval))
+ (import "env" "switch" (func $switch (param i32 i32 i32 i32)))
+ (global $HEAP_BASE i32 (i32.const 4))
+ (global $FLT i32 (f32.const -4.0))
+ (global $DBL i32 (f64.const -4.0))
+ (func $test/switch/case/eval (; 0 ;) (type $i) (param $0 i32) (result i32)
+  (if (result i32)
+   (i32.eqz
+    (get_global $HEAP_BASE)
+   )
+   (i32.const 0)
+   (get_local $0)
+  )
+ )
+)