wasmtest: fix resource cleanup and add logging

The chromedp context was not cancelled, so resources may have been leaking.
Additionally this waits for the browser to start before the timer starts, and extends the timeout to 20 seconds.
Logging from chromedp has also been enabled, which may help identify possible issues?

tests/wasm/setup_test.go

@@ -32,16 +32,21 @@ func runargs(t *testing.T, args ...string) error {
 	return nil
 }
 
-func chromectx() (context.Context, context.CancelFunc) {
-
-	var ctx context.Context
-
+func chromectx(t *testing.T) context.Context {
 	// looks for locally installed Chrome
-	ctx, _ = chromedp.NewContext(context.Background())
+	ctx, ccancel := chromedp.NewContext(context.Background(), chromedp.WithErrorf(t.Errorf), chromedp.WithDebugf(t.Logf), chromedp.WithLogf(t.Logf))
+	t.Cleanup(ccancel)
 
-	ctx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	// Wait for browser to be ready.
+	err := chromedp.Run(ctx)
+	if err != nil {
+		t.Fatalf("failed to start browser: %s", err.Error())
+	}
 
-	return ctx, cancel
+	ctx, tcancel := context.WithTimeout(ctx, 30*time.Second)
+	t.Cleanup(tcancel)
+
+	return ctx
 }
 
 func startServer(t *testing.T) (string, *httptest.Server) {