Re-introduce Web examples (#3637)

examples/util/tracing.rs

@@ -0,0 +1,27 @@
+#[cfg(not(web_platform))]
+pub fn init() {
+    use tracing_subscriber::filter::{EnvFilter, LevelFilter};
+
+    tracing_subscriber::fmt()
+        .with_env_filter(
+            EnvFilter::builder()
+                .with_default_directive(LevelFilter::INFO.into())
+                .from_env_lossy(),
+        )
+        .init();
+}
+
+#[cfg(web_platform)]
+pub fn init() {
+    use tracing_subscriber::layer::SubscriberExt;
+    use tracing_subscriber::util::SubscriberInitExt;
+
+    tracing_subscriber::registry()
+        .with(
+            tracing_subscriber::fmt::layer()
+                .with_ansi(false)
+                .without_time()
+                .with_writer(tracing_web::MakeWebConsoleWriter::new()),
+        )
+        .init();
+}