runtime: add syscall/js stubs for microcontrollers

src/runtime/override_js.go

@@ -0,0 +1,18 @@
+// +build js,arm avr
+
+package runtime
+
+// This file stubs out some external functions declared by the syscall/js
+// package. They cannot be used on microcontrollers.
+
+type js_ref uint64
+
+//go:linkname js_valueGet syscall/js.valueGet
+func js_valueGet(v js_ref, p string) js_ref {
+	return 0
+}
+
+//go:linkname js_valueNew syscall/js.valueNew
+func js_valueNew(v js_ref, args []js_ref) (js_ref, bool) {
+	return 0, true
+}