[minor] Change expression evaluation cli argument to -Xexpression

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JVMCompilerArguments.kt

@@ -49,7 +49,7 @@ class K2JVMCompilerArguments : CommonCompilerArguments() {
     @Argument(value = "-no-reflect", description = "Don't automatically include Kotlin reflection into the classpath")
     var noReflect: Boolean by FreezableVar(false)
 
-    @Argument(value = "-expression", description = "Evaluate the given string as a Kotlin script")
+    @Argument(value = "-Xexpression", description = "Evaluate the given string as a Kotlin script")
     var expressions: Array<String>? by FreezableVar(null)
 
     @Argument(

compiler/cli/cli-runner/src/org/jetbrains/kotlin/runner/runners.kt

@@ -152,7 +152,7 @@ class ExpressionRunner(private val code: List<String>) : RunnerWithCompiler() {
         val compilerArgs = ArrayList<String>().apply {
             addClasspathArgIfNeeded(classpath)
             code.forEach {
-                add("-expression")
+                add("-Xexpression")
                 add(it)
             }
             addAll(arguments)