accept fdread event as valid behavior of stdin poll

crates/test-programs/tests/wasm_tests/runtime/cap_std_sync.rs

@@ -1,5 +1,4 @@
 use anyhow::Context;
-use std::convert::TryInto;
 use std::path::Path;
 use wasi_cap_std_sync::WasiCtxBuilder;
 use wasi_common::pipe::{ReadPipe, WritePipe};
@@ -89,21 +88,6 @@ pub fn instantiate_inherit_stdio(
     let r = {
         let store = Store::default();
 
-        // Tests assume that stdin does not have any bytes available to read. Make sure this is the
-        // case, regardless of the test environment:
-        use std::io::Read;
-        use system_interface::io::ReadReady;
-        let nbytes = std::io::stdin()
-            .num_ready_bytes()
-            .expect("get stdin's ready bytes");
-        if nbytes > 0 {
-            let mut stdin_contents = Vec::new();
-            stdin_contents.resize(nbytes.try_into().expect("ready bytes fits in memory"), 0);
-            std::io::stdin()
-                .read(stdin_contents.as_mut_slice())
-                .expect("read stdin to end");
-        }
-
         // Create our wasi context.
         // Additionally register any preopened directories if we have them.
         let mut builder = WasiCtxBuilder::new();