fix context for cascade-saving and saving existing object (#6735)

* added test cases

* fixed unparsed context when updating object

* fixed context inheritance for cascade-saved objects

* upgraded parse dependecy to 2.14.0

* rebuild

* removed superfluous comments

* undo lint changes

src/RestWrite.js

@@ -52,12 +52,13 @@ function RestWrite(
     this.runOptions.action = action;
   }
 
+  // Parse context
+  if (data._context && data._context instanceof Object) {
+    this.context = data._context;
+    delete data._context;
+  }
+
   if (!query) {
-    // Parse context
-    if (data._context && data._context instanceof Object) {
-      this.context = data._context;
-      delete data._context;
-    }
     if (this.config.allowCustomObjectId) {
       if (
         Object.prototype.hasOwnProperty.call(data, 'objectId') &&