since BuiltInsReferenceResolver is initialized on-demand, we can't use async initialization

idea/idea-analysis/src/org/jetbrains/kotlin/idea/references/BuiltInsReferenceResolver.kt

@@ -63,7 +63,7 @@ public class BuiltInsReferenceResolver(val project: Project, val startupManager:
 
         val jetBuiltInsFiles = getJetBuiltInsFiles()
 
-        val initializeRunnable = { ->
+        runReadAction {
             val newModuleContext = ContextForNewModule(project, Name.special("<built-ins resolver module>"), ModuleParameters.Empty)
             newModuleContext.setDependencies(newModuleContext.module)
 
@@ -88,15 +88,6 @@ public class BuiltInsReferenceResolver(val project: Project, val startupManager:
             builtinsPackageFragment = fragments.single()
             builtInsSources = jetBuiltInsFiles
         }
-
-        if (ApplicationManager.getApplication().isUnitTestMode()) {
-            initializeRunnable()
-        }
-        else {
-            ApplicationManager.getApplication().executeOnPooledThread {
-                runReadAction { initializeRunnable() }
-            }
-        }
     }
 
     private fun getJetBuiltInsFiles(): Set<JetFile> {