Preprocess script dependencies before running UnusedSymbolInspection

^KT-29474

idea/idea-core/src/org/jetbrains/kotlin/idea/core/script/ScriptDependenciesUpdater.kt

@@ -75,6 +75,22 @@ class ScriptDependenciesUpdater(
         return cache[file] ?: ScriptDependencies.Empty
     }
 
+    fun updateDependenciesIfNeeded(files: List<VirtualFile>): Boolean {
+        val definitionsManager = ScriptDefinitionsManager.getInstance(project)
+        if (definitionsManager.isReady() && areDependenciesCached(files)) {
+            return false
+        }
+
+        for (file in files) {
+            val scriptDef = file.findScriptDefinition(project) ?: continue
+            updateDependencies(file, scriptDef)
+        }
+
+        makeRootsChangeIfNeeded()
+
+        return true
+    }
+
     private fun updateDependencies(file: VirtualFile, scriptDef: KotlinScriptDefinition) {
         val loader = when (scriptDef.dependencyResolver) {
             is AsyncDependenciesResolver, is LegacyResolverWrapper -> asyncLoader
@@ -154,6 +170,10 @@ class ScriptDependenciesUpdater(
         return cache[file] != null
     }
 
+    private fun areDependenciesCached(files: List<VirtualFile>): Boolean {
+        return files.all { areDependenciesCached(it) }
+    }
+
     companion object {
         @JvmStatic
         fun getInstance(project: Project): ScriptDependenciesUpdater =