Bind tasks' run function to prevent loosing this context (elastic#35933…

…) (elastic#35936)

* Bind tasks' run function to prevent loosing this context

* Add .node_binaries to build cleanup too

.node_binaries were previously added to yarn kbn cleanup but this
is different than the cleanup task that gets run as part of the
build.

src/dev/build/tasks/clean_tasks.js

@@ -29,6 +29,7 @@ export const CleanTask = {
     await deleteAll([
       config.resolveFromRepo('build'),
       config.resolveFromRepo('target'),
+      config.resolveFromRepo('.node_binaries'),
     ], log);
   },
 };

src/dev/build/tasks/nodejs/extract_node_builds_task.js

@@ -29,7 +29,7 @@ const statAsync = promisify(fs.stat);
 const mkdirpAsync = promisify(mkdirp);
 const copyFileAsync = promisify(fs.copyFile);
 
-export const ExtractNodeBuildsTask = {
+const ExtractNodeBuildsTask = {
   global: true,
   description: 'Extracting node.js builds for all platforms',
   async run(config) {
@@ -55,3 +55,7 @@ export const ExtractNodeBuildsTask = {
     return await copyFileAsync(source, destination, fs.constants.COPYFILE_FICLONE);
   },
 };
+
+ExtractNodeBuildsTask.run = ExtractNodeBuildsTask.run.bind(ExtractNodeBuildsTask);
+
+export { ExtractNodeBuildsTask };