Misc: Protect freeArgs with FreezableVar

jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/build/AbstractLookupTrackerTest.kt

@@ -138,7 +138,7 @@ abstract class AbstractJsLookupTrackerTest : AbstractLookupTrackerTest() {
         val args = K2JSCompilerArguments().apply {
             outputFile = File(outDir, "out.js").canonicalPath
             reportOutputFiles = true
-            freeArgs.addAll(filesToCompile.map { it.canonicalPath })
+            freeArgs = filesToCompile.map { it.canonicalPath }
         }
         return runJSCompiler(args, env)
     }

jps-plugin/jps-tests/test/org/jetbrains/kotlin/jps/incremental/AbstractJsProtoComparisonTest.kt

@@ -56,7 +56,7 @@ abstract class AbstractJsProtoComparisonTest : AbstractProtoComparisonTest<Proto
             outputFile = File(outputDir, "out.js").canonicalPath
             metaInfo = true
             main = K2JsArgumentConstants.NO_CALL
-            freeArgs.addAll(ktFiles)
+            freeArgs = ktFiles
         }
 
         val env = createTestingCompilerEnvironment(messageCollector, outputItemsCollector, services)