Fix: Use Vars instead of plain assignments for declaration imports

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/IrModuleToJsTransformer.kt

@@ -222,12 +222,7 @@ class IrModuleToJsTransformer(
                 .forEach { declaration ->
                     val declName = getNameForExternalDeclaration(declaration)
                     importStatements.add(
-                        JsExpressionStatement(
-                            jsAssignment(
-                                declName.makeRef(),
-                                JsNameRef(declName, qualifiedReference)
-                            )
-                        )
+                        JsVars(JsVars.JsVar(declName, JsNameRef(declName, qualifiedReference)))
                     )
                 }
         }

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/utils/StableNamesCollector.kt

@@ -105,7 +105,7 @@ private val RESERVED_IDENTIFIERS = setOf(
 
     "Error", "Object", "Number",
 
-    "Math", "String", "Boolean", "Date", "Array", "RegExp", "JSON",
+    "Math", "String", "Boolean", "Date", "Array", "RegExp", "JSON", "Map",
 
     // global identifiers usually declared in know environments (node.js, browser, require.js, WebWorkers, etc)
     "require", "define", "module", "window", "self"