[JS DCE] Add an ability to define overwriting strategy when copying dependencies in dev-mode

* CLI option "-Xdev-mode-overwriting-strategy"
* System Property "kotlin.js.dce.devmode.overwriting.strategy"

Possible values: "older", "all".

#KT-36349 Fixed

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/K2JSDceArguments.kt

@@ -1,21 +1,13 @@
 /*
- * Copyright 2010-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.cli.common.arguments
 
+import org.jetbrains.kotlin.cli.common.arguments.DevModeOverwritingStrategies.ALL
+import org.jetbrains.kotlin.cli.common.arguments.DevModeOverwritingStrategies.OLDER
+
 class K2JSDceArguments : CommonToolArguments() {
     companion object {
         @JvmStatic private val serialVersionUID = 0L
@@ -48,4 +40,16 @@ class K2JSDceArguments : CommonToolArguments() {
     )
     @GradleOption(DefaultValues.BooleanFalseDefault::class)
     var devMode: Boolean by FreezableVar(false)
+
+    @Argument(
+        value = "-Xdev-mode-overwriting-strategy",
+        valueDescription = "{$OLDER|$ALL}",
+        description = "Overwriting strategy during copy dependencies in development mode"
+    )
+    var devModeOverwritingStrategy: String? by NullableStringFreezableVar(null)
+}
+
+object DevModeOverwritingStrategies {
+    const val OLDER = "older"
+    const val ALL = "all"
 }