add empty contract

runner/index.html

@@ -255,7 +255,7 @@
             imports.env.memory = runtime.memory;
           }
           if (!imports.env.table) {
-            imports.env.table = new WebAssembly.Table({ initial: 6, maximum: 6, element: 'anyfunc' });
+            imports.env.table = new WebAssembly.Table({ initial: 0, maximum: 0, element: 'anyfunc' });
           }
           return new WebAssembly.Instance(module, imports);
         });

samples/empty_contract.rs

@@ -0,0 +1,12 @@
+#![feature(link_args)]
+#![no_main]
+
+// as it is experimental preamble
+#![allow(dead_code)]
+
+#[link_args = "-s WASM=1 -s NO_EXIT_RUNTIME=1 -s NO_FILESYSTEM=1 -s"]
+extern {}
+
+#[no_mangle]
+pub fn call() {
+}