watcher for rescript syntax

Author: bobzhang

jscomp/test/hello_res.res

@@ -1,4 +1,17 @@
+@@config({
+    flags : [
+        "-dparsetree"
+    ]
+})
 
 let b = List.length(list{1,2,3})
 let a = b - 1
-Js.log ("hello, res")
+Js.log ("hello, res")
+
+type t = { "x" : int }
+
+
+
+let u : t = {"x" : 3 }
+
+let h = u["x"]

scripts/tasks.js

@@ -87,7 +87,9 @@ function onSourceChange(eventType, filename) {
     filename.endsWith(".mli") ||
     filename.endsWith(".json") ||
     filename.endsWith(".re") || 
-    filename.endsWith(".rei")
+    filename.endsWith(".rei") ||
+    filename.endsWith(".res") ||
+    filename.endsWith(".resi")
   ) {
     rebuild();
   }