Minor, fix some warnings such as "unused main argument" in generators

js/js.tests/test/org/jetbrains/kotlin/generators/tests/GenerateJsTests.kt

@@ -14,7 +14,7 @@ import org.jetbrains.kotlin.js.test.semantics.*
 import org.jetbrains.kotlin.js.test.wasm.semantics.AbstractIrWasmBoxWasmTest
 import org.jetbrains.kotlin.test.TargetBackend
 
-fun main(args: Array<String>) {
+fun main() {
     System.setProperty("java.awt.headless", "true")
 
     // TODO: repair these tests

js/js.tests/test/org/jetbrains/kotlin/generators/tests/generateTestDataForReservedWords.kt

@@ -39,7 +39,7 @@ private val commonCases: CaseBuilder.(String, String) -> Unit = { testByName, te
 
 private val commonCasesWithTestNotRenamed: CaseBuilder.() -> Unit = { commonCases(testNotRenamedByName, testNotRenamedByRef) }
 
-fun main(args: Array<String>) {
+fun main() {
     generateTestDataForReservedWords()
 }
 

js/js.tests/test/org/jetbrains/kotlin/js/test/EncodeSignatureTest.kt

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.js.test
 import com.intellij.mock.MockVirtualFileSystem
 import com.intellij.openapi.Disposable
 import com.intellij.openapi.util.Disposer
+import com.intellij.openapi.vfs.VirtualFileSystem
 import com.intellij.psi.PsiManager
 import org.jetbrains.kotlin.cli.jvm.compiler.EnvironmentConfigFiles
 import org.jetbrains.kotlin.cli.jvm.compiler.KotlinCoreEnvironment
@@ -203,7 +204,7 @@ class EncodeSignatureTest {
             val project = environment.project
 
             val fs = MockVirtualFileSystem()
-            val file = fs.file("sample.kt", codeSnippet).findFileByPath("/sample.kt")
+            val file = (fs.file("sample.kt", codeSnippet) as VirtualFileSystem).findFileByPath("/sample.kt")!!
             val psiManager = PsiManager.getInstance(project)
             val psiFile = psiManager.findFile(file) as KtFile