wasm: support wasm example on Safari

src/examples/wasm/wasm.js

@@ -13,11 +13,23 @@ function init() {
   document.querySelector('#b').oninput = updateResult;
 
   const go = new Go();
-  WebAssembly.instantiateStreaming(fetch(WASM_URL), go.importObject).then(function(obj) {
-    wasm = obj.instance;
-    go.run(wasm);
-    updateResult();
-  })
+  if ('instantiateStreaming' in WebAssembly) {
+    WebAssembly.instantiateStreaming(fetch(WASM_URL), go.importObject).then(function(obj) {
+      wasm = obj.instance;
+      go.run(wasm);
+      updateResult();
+    })
+  } else {
+    fetch(WASM_URL).then(resp =>
+      resp.arrayBuffer()
+    ).then(bytes =>
+      WebAssembly.instantiate(bytes, go.importObject).then(function(obj) {
+        wasm = obj.instance;
+        go.run(wasm);
+        updateResult();
+      })
+    )
+  }
 }
 
 init();