IR: IrTypeAlias: Strip 'typealias' declarations in back-ends

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt

@@ -98,6 +98,12 @@ private val lateinitLoweringPhase = makeJsModulePhase(
     description = "Insert checks for lateinit field references"
 )
 
+private val stripTypeAliasDeclarationsPhase = makeJsModulePhase(
+    { StripTypeAliasDeclarationsLowering() },
+    name = "StripTypeAliasDeclarations",
+    description = "Strip typealias declarations"
+)
+
 // TODO make all lambda-related stuff work with IrFunctionExpression and drop this phase
 private val provisionalFunctionExpressionPhase = makeJsModulePhase(
     { ProvisionalFunctionExpressionLowering() },
@@ -396,6 +402,7 @@ val jsPhases = namedIrModulePhase(
     lower = validateIrBeforeLowering then
             testGenerationPhase then
             expectDeclarationsRemovingPhase then
+            stripTypeAliasDeclarationsPhase then
             provisionalFunctionExpressionPhase then
             arrayConstructorPhase then
             functionInliningPhase then