Move worker integration into entrypoint for wasmparser_worker

This allows us to test the wasmparser_worker implementation
in isolation in unit tests, while extracting out the worker
integration into a separate file. A follow-up CL will migrate
the wasmparser_worker to use URL-based worker construction,
which will allow us to remove the wasmparser_worker-entrypoint
in front_end/ and cleanup the RuntimeInstantiator.js logic.

[email protected],[email protected]

Bug: 1009443
Change-Id: I77d04ab870b38ec9f9209c1a156c123c941d169b
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2581927
Commit-Queue: Tim van der Lippe <[email protected]>
Reviewed-by: Jack Franklin <[email protected]>
Reviewed-by: Benedikt Meurer <[email protected]>
diff --git a/front_end/startup/RuntimeInstantiator.js b/front_end/startup/RuntimeInstantiator.js
index 0f11d0f..562f87a 100644
--- a/front_end/startup/RuntimeInstantiator.js
+++ b/front_end/startup/RuntimeInstantiator.js
@@ -88,6 +88,7 @@
   return startApplication(appName).then(sendWorkerReady);
 
   function sendWorkerReady() {
+    // @ts-ignore
     self.postMessage('workerReady');
   }
 }