[JS] Extract sourcemap generating related files to a separate module

It's required to reuse the same infrastructure in the new backend.

js/js.dce/build.gradle.kts

@@ -8,6 +8,7 @@ dependencies {
     compile(project(":compiler:util"))
     compile(project(":js:js.ast"))
     compile(project(":js:js.translator"))
+    compileOnly(project(":js:js.sourcemap"))
     compileOnly(intellijCoreDep()) { includeJars("intellij-core") }
     compileOnly(intellijDep()) { includeJars("guava", rootProject = rootProject) }
 }

js/js.dce/src/org/jetbrains/kotlin/js/dce/DeadCodeElimination.kt

@@ -1,17 +1,6 @@
 /*
- * 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 2010-2021 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.js.dce
@@ -24,7 +13,7 @@ import org.jetbrains.kotlin.js.backend.ast.JsGlobalBlock
 import org.jetbrains.kotlin.js.backend.ast.JsNode
 import org.jetbrains.kotlin.js.backend.ast.JsProgram
 import org.jetbrains.kotlin.js.dce.Context.Node
-import org.jetbrains.kotlin.js.facade.SourceMapBuilderConsumer
+import org.jetbrains.kotlin.js.sourceMap.SourceMapBuilderConsumer
 import org.jetbrains.kotlin.js.inline.util.collectDefinedNames
 import org.jetbrains.kotlin.js.inline.util.fixForwardNameReferences
 import org.jetbrains.kotlin.js.parser.parse
@@ -159,4 +148,4 @@ class DeadCodeElimination(
             }
         }
     }
-}
+}